[ci skip] fix typo still -> will

The column is primarily used for type casting, which we're trying to
separate from the idea of a column. Since what we really need is the
combination of a name, type, and value, let's use the object that we
already have to represent that concept, rather than this tuple. No
consumers of the bind values have been changed, only the producers
(outside of tests which care too much about internals). This is
*finally* possible since the bind values are now produced from a
reasonable number of lcoations.

I'm going to be extracting this logic into a clause class, things need
to go through a method and not access the values hash directly.

Attempting to grok this code by refactoring it as I go through it.

The only place it was accessed was in tests. Many of them have another
way that they can test their behavior, that doesn't involve reaching
into internals as far as they did. `AssociationScopeTest` is testing a
situation where the where clause would have one bind param per
predicate, so it can just ignore the predicates entirely. The where
chain test was primarly duplicating the logic tested on `WhereClause`
directly, so I instead just make sure it calls the appropriate method
which is fully tested in isolation.

The bind values can come from four places. `having`, `where`, `joins`,
and `from` when selecting from a subquery that contains binds. These
need to be kept in a specific order, since the clauses will always
appear in that order. Up until recently, they were not.

Additionally, `joins` actually did keep its bind values in a separate
location (presumably because it's the only case that people noticed was
broken). However, this meant that anything accessing just `bind_values`
was broken (which most places were). This is no longer possible, there
is only a single way to access the bind values, and it includes joins in
the proper location. The setter was removed yesterday, so breaking `+=`
cases is not possible.

I'm still not happy that `joins` is putting it's bind values on the
Arel AST, and I'm planning on refactoring it further, but this removes a
ton of bug cases.

Fix typo on guide name

3729103e

[ci skip]

Update ActiveRecord::ModelSchema#table_name= 's doc

Overriding these methods may cause unexpected results since
"table_name=" does more then just setting the "@table_name".

ref: https://github.com/rails/rails/pull/18622#issuecomment-70874358

Contrary to my previous commit message, it wasn't overkill, and led to
much cleaner code.

[Sean Griffin & anthonynavarre]

The last place that was assigning it was when `from` is called with a
relation to use as a subquery. The implementation was actually
completely broken, and would break if you called `from` more than once,
or if you called it on a relation, which also had its own join clause,
as the bind values would get completely scrambled. The simplest solution
was to just move it into its own array, since creating a `FromClause`
class for this would be overkill.

All of its uses have been moved to better places

This removes the need to duplicate much of the logic in `WhereClause`
and `PredicateBuilder`, simplifies the code, removes the need for the
connection adapter to be continuously passed around, and removes one
place that cares about the internal representation of `bind_values`

Part of the larger refactoring to change how binds are represented
internally

[Sean Griffin & anthonynavarre]

The Relation will ultimately end up holding a reference to the arel
table object, and its associated type caster. If this is a
`TypeCaster::Connection`, that means it'll hold a reference to the
connection adapter, which cannot be marshalled. We can work around this
by just holding onto the class object instead. It's ugly, but I'm hoping
to remove the need for the connection adapter type caster in the future
anyway.

[Sean Griffin & anthonynavarre]

PG expects us to not give it nonsenes

[Sean Griffin & anthonynavarre]

This fixed an issue where `having` can only be called after the last
call to `where`, because it messes with the same `bind_values` array.
With this change, the two can be called as many times as needed, in any
order, and the final query will be correct. However, once something
assigns `bind_values`, that stops. This is because we have to move all
of the bind values from the having clause over to the where clause since
we can't differentiate the two, and assignment was likely in the form
of:

`relation.bind_values += other.bind_values`

This will go away once we remove all places that are assigning
`bind_values`, which is next on the list.

While this fixes a bug that was present in at least 4.2 (more likely
present going back as far as 3.0, becoming more likely in 4.1 and later
as we switched to prepared statements in more cases), I don't think this
can be easily backported. The internal changes to `Relation` are
non-trivial, anything that involves modifying the `bind_values` array
would need to change, and I'm not confident that we have sufficient test
coverage of all of those locations (when `having` was called with a hash
that could generate bind values).

[Sean Griffin & anthonynavarre]

When we made sure that the counter gets updated in memory, we only did
it on the has many side. The has many side only does the update if the
belongs to cannot. The belongs to side was updated to update the counter
cache (if it is able). This means that we need to check if the
belongs_to is able to update in memory on the has_many side.

We also found an inconsistency where the reflection names were used to
grab the association which should update the counter cache. Since
reflection names are now strings, this means it was using a different
instance than the one which would have the inverse instance set.

Fixes #18689

[Sean Griffin & anthonynavarre]

There are many ways that things end up getting passed to `concat`. Not
all of those entry points called `flatten` on their input. It seems that
just about every method that is meant to take a single record, or that
splats its input, is meant to also take an array. `concat` is the
earliest point that is common to all of the methods which add records to
the association. Partially fixes #18689

It's under private in Active Model as well.

We've now removed all uses of them across the board. All logic lives on
`WhereClause`.

The code assumes that non-single-value methods mean multi value methods.
That is not the case. We need to change the accessor name, and only
assign an array for multi value methods

We're still using it in `where_unscoping`, which will require moving
additional logic.

This will make it easy to add `having_clause` and `join_clause` later.

Yes, I know, I called it a factory so I'm basically the worst person
ever who loves Java and worships the Gang of Four.

Bind values are no longer a thing, so this is unnecessary.

This object being a black box, it knows the details of how to merge
itself with another where clause. This removes all references to where
values or bind values in `Relation::Merger`