Add support for GraphQL

[mazza-av]

This PR intends to replace #2088 and closes #1634.

I have attempted to address the comments left by @jeanas.

• Passes tox -e check and tox -e test
• Replaces Text with Whitespace
• Unicode in the identifiers is not supported RFC: extend identifiers to support non-ASCII characters. graphql/graphql-spec#256

[jeanas]

There is an error in CI:

E     File "/home/runner/work/pygments/pygments/pygments/lexers/graphql.py", line 119
E       ("\}", Punctuation, "#pop"),
E        ^
E   SyntaxError: invalid escape sequence

[jeanas]

@mazza-av I've added some commits to simplify your lexer, eliminating redundant states.

Let me know if that looks good. If so I'll merge it.

[mazza-av]

@jeanas the changes look good to me. I've added a docstring to the lexer that was missing.

[jeanas]

Thank you!

[kiran94]

Thanks @jeanas and @mazza-av 😄

I'm unfamiliar with the pygments release cycle. Would you be able to help me understand when this change would be released to pypi?

[Anteru]

I try to make a release once a quarter. So sometime late July/early August for this feature, as new lexers etc. go into a new minor release (whereas we make point releases as needed.)