ActiveRecord::ConnectionAdapters::Column.string_to_time method respects string with timezone.

Closes #12278
Closes #12459

Conflicts:
	activerecord/CHANGELOG.md
Add integration test for #12459
Merge pull request #13207 from georgeguimaraes/backports-12290-to-4-0-stable

Backports #12290 to 4-0-stable. Closes #12459