Add OASv2 and OASv3 languages

[alfred-sa]

Description

Add OASv2 and OASv3 disambiguation as heuristics for JSON and YAML (see #6115)

Checklist:

• I am adding a new language.
  • The extension of the new language is used in hundreds of repositories on GitHub.com.
  • I have included a real-world usage sample for all extensions added in this PR
  • I have included a syntax highlighting grammar: (I have reused YAML and JSON grammars)
  • I have updated the heuristics to distinguish my language from others using the same extension.

[lildude]

See inline comments.

The ghes-3.4.* samples are also massive. Please replace these with much smaller samples (ProTip: it the diff collapses them, they're too big 😉).

[alfred-sa]

I have implemented all requested changes.
I know that OAS is data but I didn't know it was possible to configure GitHub to show that in languages card, that is why I set it to programming. In that regards, I didn't find how to override this setting, can you please guide me?

[lildude]

In that regards, I didn't find how to override this setting, can you please guide me?

https://github.com/github/linguist/blob/master/docs/overrides.md#detectable

Whoops. Spotted a problem

[lildude]

I've just noticed you've not added tests specifically for your new heuristics for matching the OAS files. Please add these.

[alfred-sa]

@lildude Yes, just added them + rebase from master for f-f merging.

Thanks !