Recognize more colors

[rwols]

Currently this server recognizes hex-encoded colors in the form of #rrggbbaa. Sublime text color schemes allow more variations. See https://www.sublimetext.com/docs/color_schemes.html#colors:ver-dev. These color schemes are written in a jsonc syntax. Ideally this server should parse those variations and present them via textDocument/documentColor.

It seems that vscode-css-language-server can already parse these kinds of variables. So that gives me an idea to port that code to vscode-json-languageservice, or perhaps they should share a common base.

Related: sublimelsp/LSP-json#59

[KapitanOczywisty]

Good point. It's a matter of replacing Provider and Tests with something similar to CSS provider and CSS tests. It's probably not worth the effort to share this code, since there will be some differences, e.g. color names probably should work only if format=color.

[aeschli]

Right now, color tags appear when the scheme specifies format=colorHex.
We would need a new format. maybe something like format=colorCSS.

I'm open to that, if you want to look into a PR...

[KapitanOczywisty]

In the early drafts there was format=color proposed as css, but afik it never made into official schema. However I think it's a good name, and this is for color provider anyway, not for validation. Alternatively maybe we should check name for color or add key color:true. I don't know how colors are written into the schemas in the wild so not sure what is the best.