re_matches_logical helper ensures logical output of re_matches_logical

[MichaelChirico]

Closes #2678.

This changes what was an error in expect_lint() into functioning code. On balance I think consistency is good here; the downside is previously user providing capture group accidentally would be met with an error steering them to improving their inputs.

[MichaelChirico]

All of the fixes are for dev-only features, so didn't update any NEWS.

[AshesITR]

I thunk we should add a bullet stating that some linters, and expect_lint() now support capture groups in their regex.

[AshesITR]

Let's add to NEWS that support for regex with capture groups was added for some linters.

[MichaelChirico]

Let's add to NEWS that support for regex with capture groups was added for some linters.

OK, PTAL. The thing is, the changes to return_linter() and todo_comment_linter() are dev-only, so a NEWS item doesn't make sense. The change for object_usage_linter() is not user-visible.