Undeprecate plural positional argument

Remove all deprecations from Action Pack

Dump index options to pretty format

`#process`, `#get`, `#post`, `#patch`, `#put`, `#delete`, and `#head`.

Remove deprecated support for passing `:path` and route path as stings in `ActionDispatch::Routing::Mapper#match`

ActionDispatch::ParamsParser class was removed in favor of
ActionDispatch::Http::Parameters so it is better to move the error
constant to the new class.

`skip_action_callback`, `skip_filter`, `before_filter`,
`prepend_before_filter`, `skip_before_filter`,
`append_before_filter`, `around_filter`
`prepend_around_filter`, `skip_around_filter`,
`append_around_filter`, `after_filter`,
`prepend_after_filter`, `skip_after_filter` and
`append_after_filter`.

```ruby
  # Before
  t.index ["firm_id", "type", "rating"], name: "company_index", order: {"rating"=>:desc}, using: :btree

  # After
  t.index ["firm_id", "type", "rating"], name: "company_index", order: { rating: :desc }, using: :btree
```

Prevent to create blank comment

Don't allow tests ac:integration to failure

correct exception class in `retry_on` example [ci skip]

If the deadlock has occurred `ActiveRecord::Deadlocked` will raise.
Ref: #25107, #26059

This reverts commit 2d6c14bc.

Fixnum and Bignum are deprecated in Ruby trunk

Currently blank comment does not dump to `db/schema.rb`. But created it
even if specified blank.

https://bugs.ruby-lang.org/issues/12739

Bump sdoc to 1.0.0.beta2 which includes fix to support Ruby 2.4

assigns assert the state of a controller instance what should not be
done in an integration test.