All indentation was normalized by rubocop auto-correct at 80e66cc4.
But heredocs was still kept absolute position. This commit aligns
heredocs indentation for consistency.

This was almost every case where we are overriding `respond_to?` in a
way that mirrors a parallel implementation of `method_missing`. There is
one remaining case in Active Model that should probably do the same
thing, but had a sufficiently strange implementation that I want to
investigate it separately.

Fixes #26333.

The current code base is not uniform. After some discussion,
we have chosen to go with double quotes by default.

Where appropriatei, prefer the more concise Regexp#match?,
String#include?, String#start_with?, or String#end_with?

This reverts commit d5ba9a42, reversing
changes made to 30c50339.

Reason: This generate the dynalic finders more than one time

Before:

  >> ActiveRecord::Base.respond_to?(:find_by_something)
  NoMethodError: undefined method `abstract_class?' for Object:Class

After:

  >> ActiveRecord::Base.respond_to?(:find_by_something)
  => false

The dynamic finder was creating the method signature with the parameters name,
which may have reserved words and this way creating invalid Ruby code.

Closes: #13261

    Example:

        # Before
        Dog.find_by_alias('dog name')

        # Was creating this method
        def self.find_by_alias(alias, options = {})

        # After
        Dog.find_by_alias('dog name')

        # Will create this method
        def self.find_by_alias(_alias, options = {})

Caches the patterns of ActiveRecord::DynamicMatchers in a class instance
variable.

It turns out this file is required in active_record.rb.

For consistency with the other AR extension plugins we are creating.

This reverts commit 14fc8b34.

Reason: we need to discuss a better path from this removal.

Conflicts:
	activerecord/lib/active_record/reflection.rb
	activerecord/test/cases/base_test.rb
	activerecord/test/models/developer.rb

previously dynamic finders only worked in combination with the actual
column name and not its alias defined with #alias_attribute

This feature adds a lot of complication to ActiveRecord for dubious
value. Let's talk about what it does currently:

class Customer < ActiveRecord::Base
  composed_of :balance, :class_name => "Money", :mapping => %w(balance amount)
end

Instead, you can do something like this:

    def balance
      @balance ||= Money.new(value, currency)
    end

    def balance=(balance)
      self[:value] = balance.value
      self[:currency] = balance.currency
      @balance = balance
    end

Since that's fairly easy code to write, and doesn't need anything
extra from the framework, if you use composed_of today, you'll
have to add accessors/mutators like that.

Closes #1436
Closes #2084
Closes #3807

* Avoid double hash lookups in AR::Reflection when reflecting associations/aggregations
* Minor cleanups: use elsif, do..end, if..else instead of unless..else
* Simplify DynamicMatchers#respond_to?
* Use "where" instead of scoped with conditions hash
* Extract `scoped_by` method pattern regexp to constant
* Extract noisy class_eval from method_missing in dynamic matchers
* Extract readonly check, avoid calling column#to_s twice in persistence
* Refactor predicate builder, remove some variables

Under Rails 3.1, you were allowed to pass a hash to a find_or_create
method with multiple attribute names, but this was broken as the
arguments were being improperly validated.