Add support for match expression

[mdomke]

This is based on the work of @g15ecb

g15ecb@988efe9

[lukelbd]

Have been using this for a while (copy-pasted your syntax file). Works fine for me so far.

[lukelbd]

Seems to need approval from @nfnty?

[cdonovick]

I have an alternate version of this 5d79f24

Mine is slightly more expensive as it avoids highlighting non keyword versions of the match case.

One note on this PR is that match / case should not appear in the pythonExpression cluster. pythonExpression is exclusively used by fstring highlighting and there is no expression form of match.

[paulbalegend]

Tested this works -- it's now over 2 years old, what is preventing it from being merged?

[sanjayankur31]

@nfnty is there a chance you could add more people to the maintainers list here so these PRs could be reviewed/merged---the last commit here is 6 years ago. I'd rather not create a personal fork, but if this is no longer maintained, it'll be good to pass it on to others (or let us know so we can fork it in a new place)?

Thanks for your work on this,