Manually set Inliner state before creating tag links/badges

[JWCook]

Fixes #42

Here's what I found:

• The missing pieces of Inliner state are set in docutils.parsers.rst.states.RSTState.inline_text() -> Inliner.parse()
  • Includes Inliner.document, reporter, and language
• So docutils is assuming that if any role is being processed, then inline_text() has already been called to parse the relevant text.
• In this case, the role is XRefBadgeRole (used to create a badge with a link), but there is no corresponding text.
• Typically, that role would have been created by putting {bdg} or {button-ref} in a document and letting sphinx-design parse it. Instead, we've skipped that step and directly made a XRefBadgeRole object.
• As long as tags wasn't the first line of the document, inline_text() would have already been called by another role or directive's run() method.
• Somehow, the equivalent path in myst-parser doesn't have the same limitation.

[melissawm]

This is awesome - thank you!! I tested locally as well, looks like this does fix the problem. Let's give this a go, I will cut a release and if anything unexpected comes up we'll fix later. Cheers!