Support marking utilities and theme values as deprecated

[thecrypticace]

wip

IntelliSense PR: tailwindlabs/tailwindcss-intellisense#1084

[thecrypticace]

Thinking out loud here. It's possible we'll want the deprecation information to be more than just a boolean. Maybe a list of suggested classes? I'm hesitant to put "message" strings in here though. I'd prefer those kinds of things were generated by the IntelliSense extension.

[thecrypticace]

So right now this is implemented in a very simple manner — affecting the classList metadata that IntelliSense uses. However, given that we have bare value support there are technically an infinite number of potential deprecated classes now or in the future this wouldn't be sufficient. I could also see a case in which a class becomes deprecated base of a specific modifier or something.

I think this means we may need something like a designSystem.classMetadata(string[]) API (an array because it would be better for IntelliSense to submit "Work" in bulk).