Prevent the extension from crashing due to unparseable Dark code

[OceanOak]

Changelog:

Parser
- Update the parser to handle unparseable code 

This PR adds :

• a new Unparseable type to the CliScript type to handle unparseable code and prevent the extension from crashing.
• a --skip-self-update flag for the LSP to prevent running the self-update while using the extension
• a "parse": "tree-sitter parse" command to tree-sitter-darklang

A stack overflow occurs when the number of tokens exceeds ~340, which is consistent with the List.map issue #5222

The issue lies in the SemanticTokens.toJson function, specifically in:

t.data
 |> Stdlib.List.map (fun d -> Json.Number(Stdlib.UInt64.toFloat d))
 |> Json.Array)

[StachuDotNet]

Looks good! A few cleanups, but then good to merge.

I see there's a few places where we're returning Errors of Strings. I didn't look too closely, and suspect that those are OK -- that their contents are basically ignored, erased by an Unparseable thing, and that it's useful to keep around that string for the time when we include a Reason along with the failures. That said, worth a quick look to make sure we aren't returning a String anywhere we shouldn't