[Cookies] Match array-based cookie domains case-insensitively

[RedZapdos123]

Description:

Issue #327 reported that array-based cookie domains were matched with exact string equality, so uppercase request hosts did not match lowercase configured domains.

This PR updates Rage::Cookies#[]= to match array-based cookie domains case-insensitively while still using the configured domain value in the Set-Cookie header.

It also adds regression tests for uppercase hosts with and without a port, and updates CHANGELOG.md.

Closes #327.

Checklist:

• I have added relevant regression test cases for this fix.
• I have run linting checks in WSL using bundle exec rubocop --except Layout/EndOfLine lib/rage/cookies.rb spec/controller/api/cookies_spec.rb.
• I have run focused tests in WSL using bundle exec rspec spec/controller/api/cookies_spec.rb.
• I have run broader regression checks in WSL using bundle exec rspec spec/controller/api spec/router/constraints_spec.rb.

Before the fix:

After the fix:

[rsamoilov]

Looks great 👍