Handler config options not being passed correctly

[Blacksmoke16]

@pawamoy I think I missed something in #13. Was testing this within my project and noticed it was failing to build. Did some debugging and determined the crystal_docs_flags aren't making it from my mkdocs.yml to CrystalCollector. My current thinking is it has to do something with https://github.com/mkdocstrings/mkdocstrings/blob/main/CHANGELOG.md#:~:text=Handlers%20must%20now%20store, but I'm not sure the proper fix is here.

Like is it enough to just do like:

# Extract handler options from handler_config if present
handler_config = config.get("handler_config", {})
if handler_config:
    crystal_docs_flags = handler_config.get("crystal_docs_flags", crystal_docs_flags)
    source_locations = handler_config.get("source_locations", source_locations)

Before BaseHandler.__init__ within __init__.py?

I'm also happy to spend some time refactoring things to be more similar to the python handler. But I also know with the introduction of https://zensical.org that there is a new mkdocstrings module in the works. So if that means this handler would need to be re-written from scratch, then maybe best to just do this quick fix and save the extra effort for that new implementation?