REP-480 Rate Limit RegEx on Query String

This is the simple version satisfying the acceptance criteria of the story.

Refer to #980 for the more complex version.
Honestly, I'm not certain. There are quite a few private finals, and one of those is instantiated in the constructor.

I think I could mock a cache and configuration and verify behavior on the cache, but then the test becomes super brittle and relies on a number of other classes. Still, it's doable and I don't mind changing this test if that's your preference.