RCFilters: Fix completely broken highlight circles

RCFilters: Fix completely broken highlight circles

- Correct highlights class name (mw-rcfilters-ui-highlights, not
  mw-rcfilters-ui-changesListWrapperWidget-highlights)
- Remove -circle class suffix that the circles don't actually have
- Go back to using float: right; instead of text-align: right;
  (you can't use text-align for things that aren't inline)
- For seen/unseen watched items, apply circle mixin to the actual
  circles themselves, not their parents

Bug: T207472
Change-Id: Iade1af4299826a4e8a2108425ace9a406f0aa8cb
Follows-Up: I76fec57ff237ba02afefcea28916d8348bac9b0e