Support semantic colors/highlighting

[nilsreichardt]

Project ID (e.g. flutter-123456): flutter-z8006cm810
Operating System & Version (e.g. macOS Monterey 12.1): 12.2.1
Browser & Version (e.g. Chome 102.0.5005.115): 102.0.5005.115 (Official Build) (arm64)

### Description

[Ehesp]

I think this is due to; #20

[Ehesp]

Ok have this working on a branch, just need to apply colours to the correct properties now. Also there's a flashing issue where the LSP server keeps piping the changes and causes a flash which needs investigating.