Make arguments to engine optional

[AndreasArvidsson]

Checklist

• [/] I have added tests
• [/] I have updated the docs and cheatsheet
• [/] I have not broken the cheatsheet

[pokey]

update from meet-up re null tree-sitter:

• if tree-sitter is null, create DisabledLanguageDefinitions that just doesn't support any languages
• remove tree-sitter debug prints
• allow null to pass to parse tree action for now and just have null check there that throws

goal for all this stuff is to allow undefined components to pass into engine, and contain all resulting null checks to createEngine, and create a DisabledFoo in response. Note that third checkbox above fails this criterion, but we don't need to be dogmatic

[AndreasArvidsson]

ready!

[pokey]

wow this PR does a lot. I started in for a quick review but there's too much going on to easily see the picture. I would be tempted to split it into 4 PRs, but how about as a compromise let's just split it into 2:

1. CommandServerApi / HatTokenMap
2. LanguageDefinitions / TreeSitter

I think that is a nice split point

See also the commit I just pushed, and comments below

[pokey]

this is no longer ever undefined right?

Suggested change

	private commandServerApi: CommandServerApi | undefined,
	private commandServerApi: CommandServerApi,

[AndreasArvidsson]

Unfortunately not. This is constructed in the extension file and does not get the disabled default implementation from the engine

[AndreasArvidsson]

Ok this pull request has now been stripped off the Tree sitter stuff

[pokey]

looks good with one minor comment!