C# highlighting improvements

[Philipp-M]

Adds more queries for better highlighting:

before:

after:

[the-mikedavis]

I haven't dug into this fully yet but it's looking like a great improvement! There are some highlights I've seen that I think would be good to include here as well if you like them:

; this list already exists and we should be able to just add "static" in
[
  ; ..
  "static"
  ; ..
] @keyword

highlights a block like so:

using Status = Google.Rpc.Status;
using static EventStore.Client.Streams.BatchAppendReq.Types;
using static EventStore.Client.Streams.BatchAppendReq.Types.Options;
using OperationResult = EventStore.Core.Messages.OperationResult;

((identifier) @comment.unused
 (#eq? @comment.unused "_"))

we've used in other languages that support pattern matching to mark it as an unused pattern.

For example in an expression like so:

Task.Delay(timeout, cancellationToken).ContinueWith(_ => onTimeout(), cancellationToken);

[Philipp-M]

Thanks for the input, I've adapted your changes

[the-mikedavis]

one more highlight I found looking at some example code:

[
  ; .. L148
  ">"
  ">="
] @operator

With that I think this will be ready to merge 👍

[Philipp-M]

I missed that there were operators that aren't covered yet, I checked this: https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/operators/#operator-precedence

And I think I covered now every operator in one way or the other (something like "?." was not possible because it's already covered by "." and "?" I guess?)

[the-mikedavis]

It's a bit confusing what can be written in strings with the query DSL: you can only write literal tokens that show up also as strings in the grammar (for example, these tokens). I don't see ?. in grammar.js - there must be some rule that parses the ? and . as separate tokens.

[the-mikedavis]

Great work! This is a big improvement 💪