Add AnalyzeOpenDocumentsOnly

[neoGeneva]

This pull request is exposing the new AnalyzeOpenDocumentsOnly feature merged into omnisharp-roslyn via OmniSharp/omnisharp-roslyn#2346

This pull request does two main things:

• Calls the fileOpen and fileClose endpoints
• Passes the new AnalyzeOpenDocumentsOnly flag as a startup parameter

And one additional weird thing I should point out:

• Calls filesChanged endpoint when an active editor changes. I found without this when switching between tabs the diagnostics would be out of date and I'd have to make a modification to force it to refresh the file, which was pretty anoying.

[JoeRobich]

@neoGeneva Thanks for the contribution! Since an O# restart is required for this option to take effect, you can add the option name to the list in this file, so that users will be prompted to restart. https://github.com/OmniSharp/omnisharp-vscode/blob/090acf09c8bd9e6802e6c2566de87cbedbc07b5b/src/observers/OptionChangeObserver.ts#L15-L27

[neoGeneva]

@JoeRobich Sweet, will do. It looks like enableRoslynAnalyzers is missing from that list too, should I add that as well?

[JoeRobich]

It looks like enableRoslynAnalyzers is missing from that list too, should I add that as well?

Ah, good catch. Please do.

[333fred]

Other than the typos, this is looking good.

[neoGeneva]

Sweet, thanks @333fred, all fixed.

[neoGeneva]

Woohoo, awesome! Thanks everybody 🙂

[JoeRobich]

@neoGeneva Thanks for the contribution! I spun up a prerelease for anyone interested in trying it out https://github.com/OmniSharp/omnisharp-vscode/releases/tag/v1.24.2-beta1