Remove inlay hints in favor of VS Code's built-in support

[xeger]

This effectively prevents ruby-syntax-tree/syntax_tree#103 from happening. It also lets us drop a setting (Code just uses the built-in colors, fonts, etc for inlay hints).

Open questions:

1. Do we bother to retain the homebrew hinting code for awhile? I'm guessing not; with only 66 installs I'm thinking this extension is still in its early days.
2. Should we perform a version check of stree at startup? It's probably not necessary (it will advertise its capabilities directly to the client) ... though I would like to do Provide a clearer error message when the stree exe cannot be spawned #13 at some point and give better guidance when no stree or no ruby can be found.

Weird, Unrelated Issue

While testing this, I noticed an oddity (not caused by this PR): the formatting only works if the file exists on disk at the time I ask to format it. For example, if the editor is a real file:

Whereas, if the editor is an unsaved buffer using the Ruby language mode:

Any idea what's up with that?!

[kddnewton]

Oh thank god this is so much cleaner. I wouldn't bother with version checking yet, this thing is not being used a ton yet.

I have no idea what's going on with the bug you mentioned. Maybe it has to do with the activation events here? https://github.com/ruby-syntax-tree/vscode-syntax-tree/blob/main/package.json#L20-L26 Maybe we should be listening for something else as well?

[xeger]

The activation hypothesis is a good one. I'll take a look if/when I delve into the double activation thing I'm seeing in the tests.