wip: Improve language server detection for workspace folders

[thecrypticace]

This is a major wip that should do a few things:

1. Potentially improved detection time in multi-root workspaces

Now we'll start the server as soon as any search has requested that it be started. Any remaining searches will be cancelled instead of waiting for them to complete. The language server itself will still do a more exhaustive search to find projects in all registered workspace folders.

2. Ignore pre-processor files that don't contain @config

Tailwind CSS v4 required us to analyze the workspace for more stylesheets that may contain @import (because @import "tailwindcss" and similar), @theme, etc… but these are only supported in .css files and not .styl, .sass, .scss, .less, etc…

We were already doing this because v3 looked for @config but that is valid in any stylesheet type. Now we restrict @import, @theme, etc matching to .css files and we'll be less likely to start the server if we don't need to.

todo: We need to apply this logic to project discovery in the server itself