Hi, this PR adds .scalafix.conf and .scalafmt.conf to the list of HOCON language filenames.

Description

Scalaformat and Scalafix both use HOCON as their configuration language, and are currently AFAICS not highlighted in any way.

Thanks!

Checklist:

• I am adding a new extension filename to a language.
  • The new extension filename is used in hundreds of repositories on GitHub.com
    • Search results for each extension filename:
      • https://github.com/search?q=path%3A*.scalafmt.conf&type=code
      • https://github.com/search?q=path%3A*.scalafix.conf&type=code
  • I have included a real-world usage sample for all extensions filenames added in this PR:
    • Sample source(s):
      • https://github.com/scalameta/scalafmt/blob/master/.scalafmt.conf
      • https://github.com/scalacenter/scalafix/blob/main/.scalafix.conf
    • Sample license(s):
      • https://github.com/scalameta/scalafmt/blob/master/LICENCE.md
      • https://github.com/scalacenter/scalafix/blob/main/LICENSE.md
  • I have included a change to the heuristics to distinguish my language from others using the same extension.