Add OverpassQL

[nickswalker]

Originally described in #6311 and added in #6709, OverpassQL support was merged then reverted in #6871 because the grammar was added incorrectly. I've reformatted the grammar and added it correctly. The rest of this PR matches #6709.

Description

Checklist:

• I am adding a new language.
  • The extension of the new language is used in hundreds of repositories on GitHub.com.
    • Search results for each extension:
      • https://github.com/search?type=code&q=NOT+is%3Afork+path%3A*.overpassql - 612 files from 200+ repositories
      • see extensive research and work by @FloEdelmann - link to github project
  • I have included a real-world usage sample for all extensions added in this PR:
    • Sample source(s):
      • written by @k-yle and given to the project under a license of its choosing in Add Overpass QL #6709 (comment)
  • I have included a syntax highlighting grammar: [URL to grammar repo]
  • I have added a color
    • Hex value: #cce2aa
    • Rationale: Sampled from the OpenStreetMap logo
  • I have updated the heuristics to distinguish my language from others using the same extension.

[lildude]

LGTM. Thanks.

Important

The changes in this PR will not appear on GitHub until the next release has been made and deployed. See here for more details.