Update to latest textmate grammar + support patterns in captures in parser

[DanTup]

@bkonyi This updates to the latest grammar, which includes a few fixes and better highlighting for interpolated strings.

Before:

After:

However, the parser did not support having patterns nested in captures so I also had to make some changes there. I extracted a PatternMatcher that matches anything that has a set of patterns (and added this to _Matcher.parse()). and now specifically look for nested patterns in captures.

With these changes, I get the same output when running some tests (see dart-lang/dart-syntax-highlight#28) as a NodeJS tool I was using to do the same. I have found some issues with the grammar (such has handling of nested type args), but I'd like to get and get some tests for the grammar (via dart-lang/dart-syntax-highlight#28) before I start trying to fix that, to ensure I don't regress anything while trying to fix (since I don't expect the fix to be trivial).

Please review carefully, I'm a parser noob :-)

Pre-launch Checklist

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[bkonyi]

It's been awhile since I've looked at the parser code, but I've looked through this a couple of times and I don't see anything obviously wrong, so LGTM.

[DanTup]

I've pushed updates to the span parser tests for latest changes, although I've found a few other differences with the NPM tool I ran that I haven't tracked down yet, so I'm going to try and get to the bottom of them before landing this (in case they're issues introduced by this change).

[kenzieschmoll]

Is this PR still blocked or is it ready to land?

[DanTup]

This isn't good to go yet. There are a few other issues with the parser I want to address before trying to upgrade to the latest grammar (which includes these additional things we don't handle). I'll close this and file a new PR when I'm ready to upgrade.