Add 2 more JavaScript interpreters

[Alhadis]

This PR registers 4 2 more JavaScript interpreters:

• Gnome JS: gjs
• MuJS: mujs ^[1]
• QuickJS: qjs
• SlimerJS: slimerjs ^[1]

Template removed as it doesn't really apply.

---

^[1] Removed after discussion with @pchaigno

[Alhadis]

@lildude No idea what's going on with CI:

  1) Error:
TestRepository#test_linguist_override_detectable?:
Rugged::OdbError: object not found - no match for id (933c687cb8c02035394979b2308e5120a9904fdf)
    /home/runner/work/linguist/linguist/lib/linguist/repository.rb:128:in `lookup'
    /home/runner/work/linguist/linguist/lib/linguist/repository.rb:128:in `current_tree'
    /home/runner/work/linguist/linguist/lib/linguist/repository.rb:123:in `read_index'
    /home/runner/work/linguist/linguist/test/test_repository.rb:149:in `test_linguist_override_detectable?'

  2) Error:
TestRepository#test_linguist_override_unvendored?:
Rugged::OdbError: object not found - no match for id (933c687cb8c02035394979b2308e5120a9904fdf)
    /home/runner/work/linguist/linguist/lib/linguist/repository.rb:128:in `lookup'
    /home/runner/work/linguist/linguist/lib/linguist/repository.rb:128:in `current_tree'
    /home/runner/work/linguist/linguist/lib/linguist/repository.rb:123:in `read_index'
    /home/runner/work/linguist/linguist/test/test_repository.rb:108:in `test_linguist_override_unvendored?'

  3) Error:
TestRepository#test_linguist_override_documentation?:
Rugged::OdbError: object not found - no match for id (933c687cb8c02035394979b2308e5120a9904fdf)
    /home/runner/work/linguist/linguist/lib/linguist/repository.rb:128:in `lookup'
    /home/runner/work/linguist/linguist/lib/linguist/repository.rb:128:in `current_tree'
    /home/runner/work/linguist/linguist/lib/linguist/repository.rb:123:in `read_index'

  4) Error:
TestRepository#test_linguist_override_generated?:
Rugged::OdbError: object not found - no match for id (933c687cb8c02035394979b2308e5120a9904fdf)
    /home/runner/work/linguist/linguist/lib/linguist/repository.rb:128:in `lookup'
    /home/runner/work/linguist/linguist/lib/linguist/repository.rb:128:in `current_tree'
    /home/runner/work/linguist/linguist/lib/linguist/repository.rb:123:in `read_index'
    /home/runner/work/linguist/linguist/test/test_repository.rb:137:in `test_linguist_override_generated?'

1330 runs, 26783 assertions, 0 failures, 4 errors, 0 skips
rake aborted!
Command failed with status (1)

Pretty sure it has nothing to do with this PR, though. 😉

[pchaigno]

Travis CI build failures seem related to the test-attributes branch and not this pull request.

/cc @lildude

[lildude]

Travis CI build failures seem related to the test-attributes branch and not this pull request.

Oh 💩 🤦‍♂ I squash merged that branch PR which added that SHA which means the SHA got stomped all over. Fix coming.