Fix migrations with enable_extension

When using ActiveRecord::Base.table_name_prefix and/or
table_name_suffix, extension names got the same treatment as table names
when running migrations. This led to migrations that tried to call, for
example, enable_extension("prefix_hstore") on the connection.
Hash#deep_*_keys(!) recurse into nested arrays.

Following methods now recursively transform nested arrays, too.

* Hash#deep_transform_keys
* Hash#deep_transform_keys!
* Hash#deep_stringify_keys
* Hash#deep_stringify_keys!
* Hash#deep_symbolize_keys
* Hash#deep_symbolize_keys!
Check authentication scheme in Basic auth

`authenticate_with_http_basic` and its families should check the authentication
schema is "Basic".

Different schema, such as OAuth2 Bearer should be rejected by basic auth, but
it was passing as the test shows.

This fixes #10257.
Run login_procedure only when the auth_scheme is valid
Fix serialized field returning serialized data after update_column
Fixes Issue #13466.

Changed the call to a scope block to be evaluated with instance_eval.
The result is that ScopeRegistry can use the actual class instead of base_class when
caching scopes so queries made by classes with a common ancestor won't leak scopes.
Fixed duplicate subscribers in ActiveSupport::Subscriber

ActiveSupport::Subscriber no longer creates multiple subscribers when
you redefine a method.
Fix `Relation#delete_all` inconsistency

When relation scopes include one of `uniq`, `group`, `having` or
`offset`, the generated query ignores them and that causes unintended
records to be deleted. This solves the issue by restricting the deletion
when those scopes are present.

rails/rails#11985
Remove unecessary require
Merge pull request #15140 from arthurnn/small_cleanup

Remove unecessary require
Reorganize ActiveRecord tasks [Arun Agrawal & Abd ar-Rahman Hamidi]
remove trailing whitespace. [ci skip]
doc, pg `hstore` and `json` columns are mapped as `Hash`. [ci skip]

Closes #15141.
Generate the cookies_serializer configuration with :marshal when upgrading

We were generating this configuration with :json what may break
applications upgrating from Rails 4.0-.

Now we always generate with a safer value and people is free to choose
hybrid if they want.

We don't generate with hybrid by default because there are some cases
that can fail. These cases are explained on the upgrading guide.
foo :bomb:
Merge pull request #15071 from leafac/issues/11985

Fix `Relation#delete_all` inconsistency
Add CHANGELOG entry for #15071 [ci skip]
Merge pull request #15037 from roccoblues/fix_duplicate_activesupport_subscribers

Fixed duplicate subscribers in ActiveSupport::Subscriber

Conflicts:
	activesupport/CHANGELOG.md
Replace first person point of view on guides.

[skip ci]
Merge pull request #15143 from htanata/first_person_pronouns

Replace first person point of view on guides.