`column_types` is empty except PostgreSQL adapter, and
`attribute_types.each_key { |k| column_types.delete k }` is also empty
even if PostgreSQL adapter almost all case, so that code is quite
useless. This improves performance for `find_by_sql` to avoid that
useless loop as much as possible.

```ruby
ActiveRecord::Schema.define do
  create_table :active_storage_blobs do |t|
    t.string   :key,          null: false
    t.string   :filename,     null: false
    t.string   :content_type
    t.text     :metadata
    t.string   :service_name, null: false
    t.bigint   :byte_size,    null: false
    t.string   :checksum,     null: false
    t.datetime :created_at,   null: false

    t.index [ :key ], unique: true
  end
end

class ActiveStorageBlob < ActiveRecord::Base
end

Benchmark.ips do |x|
  x.report("find_by") { ActiveStorageBlob.find_by(id: 1) }
end
```

Before:

```
Warming up --------------------------------------
             find_by     1.256k i/100ms
Calculating -------------------------------------
             find_by     12.595k (± 3.4%) i/s -     64.056k in   5.091599s
```

After:

```
Warming up --------------------------------------
             find_by     1.341k i/100ms
Calculating -------------------------------------
             find_by     13.170k (± 3.5%) i/s -     67.050k in   5.097439s
```

To avoid column types loop for PostgreSQL adapter, this skips returning
additional column types if a column has already been type casted by pg
decoders. Fortunately this fixes #36186 partly for common types.

https://buildkite.com/rails/rails/builds/68559#2decc846-c6b5-46f7-a805-426a8063d36c/1016-1027

Remove useless type cast on aggregated value

Update pg gem required version to 1.1

Relying on the `Arel::Table.engine` is convenient if an app have only a
single kind of database, but if not so, the global state is not always
the same with the current connection.

Batch attribute methods definition

Add override of unary plus for `ActiveSupport::Duration`

Deprecate `allowed_index_name_length` in `DatabaseLimits`

```ruby
(+ 1.second).class
=> ActiveSupport::Duration
```

Fixes #39079.

The less we depend on require_dependency, the better.

`allowed_index_name_length` was used for internal temporary operations
in SQLite3, since index name in SQLite3 must be globally unique and
SQLite3 doesn't have ALTER TABLE feature (so it is emulated by creating
temporary table with prefix).

`allowed_index_name_length` was to reserve the margin for the prefix,
but actually SQLite3 doesn't have a limitation for identifier name
length, so the margin has removed at 36901e6e.

Now `allowed_index_name_length` is no longer relied on by any adapter,
so I'd like to remove the internal specific method which is no longer
used.

Improve zeitwerk:check warning message [CI skip]

Related #39039.

Currently PostgreSQL adapter is the only adapter that rely on type
casting by `result.column_types`, now the adapter can return numeric
value without type casting by Active Record side.
So we can remove that useless type cast on aggregated value.

Actually SQLite3 doesn't have a limitation for identifier name length,
so do not need `- 2` margin internally to perform temporary rename
operations.

This reverts commit 43503bdf.

Remove confusing json by default from testing guide

```ruby
class Post < ActiveRecord::Base
end

posts = Post.where(id: 1, title: "foo")

Benchmark.ips do |x|
  x.report("scope_for_create") { posts.scope_for_create }
end
```

Before:

```
Warming up --------------------------------------
    scope_for_create    30.125k i/100ms
Calculating -------------------------------------
    scope_for_create    334.033k (± 4.4%) i/s -      1.687M in   5.060493s
```

After:

```
Warming up --------------------------------------
    scope_for_create    35.088k i/100ms
Calculating -------------------------------------
    scope_for_create    388.603k (±11.8%) i/s -      1.930M in   5.080998s
```

Define `value_for_database` and `value_before_type_cast` methods, and
use those.

check for metadata table support

This is required for #39063 to use `PG::TextDecoder::Numeric`.

Ref https://github.com/ged/ruby-pg/pull/25.

The pg gem 1.1.0 was released at August 24, 2018, so I think it is good
timing to bump the required version for improving and cleaning up the
code base.

https://rubygems.org/gems/pg/versions

Deprecate `in_clause_length` in `DatabaseLimits`

Remove redundant begin block from yarn template

This reverts commit 960ceb23.

Ref #39012, #38858.

[ci skip]

Require time core extensions in all environments

These have been required in the generated test environment config since
1c7207a2, but the generated development
config also uses them (albeit inside a conditional), and the generated
production config contains a comment which uses them.

More generally, we shouldn't require core extensions in one environment
and not others, since applications with `config.active_support.bare`
enabled could rely on them implicitly and exhibit inconsistent behaviour
across environments.

`in_clause_length` was added at c5a284f8 to address to Oracle IN clause
length limitation.

Now `in_clause_length` is entirely integrated in Arel visitor since
#35838 and #36074.

Since Oracle visitors are the only code that rely on `in_clause_length`.
so I'd like to remove that from Rails code base, like has removed Oracle
visitors (#38946).

Improve `WhereClause#ast` to make concise Arel ast

Fix aggregate functions to return numeric value consistently even on custom attribute type

Merge pull request #39048 from abhaynikam/fix-failing-test-for-upsert-all-on-relation-for-sqlite-adapter

Skip test cases for upsert_all on relation for sqlite adapter for duplicate record

Skip test cases for upsert_all on relation if database adapter doesn't support update on duplicate records