Add .eslint-ignore as ignore list filename

[spenserblack]

Description

Encountered "in the wild" in the VS Code repo

Checklist:

• I am adding a new extension filename to a language.
  • The new extension is used in hundreds of repositories on GitHub.com (currently 317)
    • Search results for each extension:
      • https://github.com/search?type=code&q=NOT+is%3Afork+path%3A%2F%28%5E%7C%5C%2F%29%5C.eslint-ignore%24%2F
  • I have included a real-world usage sample for all extensions added in this PR:
    • Sample source(s):
      • https://github.com/microsoft/vscode/blob/6149246c909a51c53114bd2db6834677bd10e8b2/.eslint-ignore
    • Sample license(s): MIT
  • I have included a change to the heuristics to distinguish my language from others using the same extension.

[Alhadis]

BTW, I noticed you used this qualifier in your search to match filenames:

path:/(^|\/)\.eslint-ignore$/

There's a less cumbersome way of matching filenames:

path:**/.eslint-ignore

[spenserblack]

There's a less cumbersome way of matching filenames:

path:**/.eslint-ignore

Thanks!