Fix `remove_index` to be able to remove expression indexes

Omit redundant `using: :btree` for schema dumping

Refactor `test_find_by_does_not_use_statement_cache_if_table_name_is_changed`

Fix unscope with subquery

The `default` arg of `index_name_exists?` makes to optional

Extract `quoted_binary` and use it rather than override `_quote`

The `default` arg of `index_name_exists?` is only used the adapter does
not implemented `indexes`. But currently all adapters implemented
`indexes` (See #26688). Therefore the `default` arg is never used.

Closes #27980

Closes #27979

`supports_primary_key?` was added to determine if `primary_key` is
implemented in the adapter in f0602214. But we already use `primary_key`
without `supports_primary_key?` (207f266c, 5f3cf424) and using
`supports_primary_key?` has been removed in #1318. This means that
`supports_primary_key?` is no longer used in the internal and Active
Record doesn't work without `primary_key` is implemented (all adapters
must implement `primary_key`).

Closes #27977

These files are not using `strip_heredoc`.

Closes #27976

Removed the `attribute_accessors` required file:

So queries are not run against the previous table name.

Closes #27953

Also not needed on this file, call to `mattr_accessor` got removed in https://github.com/rails/rails/commit/9e98f3f7e61dfce0a48948c8d296400af8bfaf21#diff-1ecd313ff0ab827af30014553cf8918dL76

- This file is no more needed, the call to `cattr_reader` were removed in https://github.com/rails/rails/commit/9e2948e750fa3f641f20adad4b4ecae89b35faa7#diff-c5146df11f35304765e9ceebed108f57L60 and https://github.com/rails/rails/commit/1fe0a1b5ebebb1372968606b85ce08b93bc145c8#diff-c5146df11f35304765e9ceebed108f57L99

Add Time#blank? to blank_test

Add `Style/EmptyLinesAroundMethodBody` in `.rubocop.yml` and remove extra empty lines

This commit is not precisely atomic, but the changes have evolved, summary:

* The ENV-based interface has been moved upwards, the generator has now a conventional
  initializer.

* RAILS_VERSION is now assumed to be a Git tag. A blank RAILS_VERSION means edge guides.

* In consequence, the EDGE env variable is gone.

* The "local" version is also gone, the current SHA1 is computed for edge guides.

* Assumes guides are generated from a repo checkout (time ago users could
  generate them from gems.)

* The WARNINGS flag is gone in consequence, you cannot disable warnings.

* The `api_link` Markdown helper is fixed.

* Docs about usage have one single place: rake guides:help.

* Links in guides have been revised.

This was never really intended to work (at least not without calling
`define_attribute_methods`, which is less common with Active Record). As
we move forward the intention is to require the use of `attribute` over
`attr_accessor` for more complex model behavior both on Active Record
and Active Model, so this behavior is deprecated.

Fixes #27956.
Close #27963.

[Alex Serban & Sean Griffin]

Switch extension 👉 format as it's more apt here.

Get TODO done in `render_test`

Currently schema dumper lost the unsigned option when primary key is
defined as bigint with unsigned. This commit fixes the issue.

Closes #27960

which is bundled in new apps by default

Delegate `to_sentence` and `to_fomatted_s` to `records`

Use released resque

Fix `test_composite_primary_key_out_of_order`

This reverts commit d6529af2.

`test_composite_primary_key_out_of_order` should use `barcodes_reverse`
table.

Update configuration guide about ActiveRecord's  use_schema_cache_dump option [ci skip]

Add note about breakage in file uploads in controller tests to upgrading guide