Refactor tests from BaseRackTest into BaseRequestTest
Fix warnings due to:
- unused variable in PG Adapter.
- Ambiguous argument warning from range_test for use - to + Infinity range without brackets.
Merge pull request #14248 from vipulnsward/fix-pg-ar-warnings

Fix PG warnings.
Merge pull request #14239 from zzak/refactor_actionpack_dispatch_request_tests

Refactor actionpack ActionDispatch::Request tests
Add a comment to ensure that a test won't be removed [ci skip]

The 'cow' => 'kine' inflection has gone with c300dca9 but it should
not be removed from the tested irregularities since it ensures that
inflections work with words that do not begin with the same letters.
Variants in ActionView::Digestor

Take variants into account when calculating template digests in
ActionView::Digest.

Digestor#digest now takes a hash as an argument to support variants and
allow more flexibility in the future. Old-style arguments have been
deprecated.

Fixes #14242