Implement pull-model documentDiagnostics (cherry-pick from main)

[tristanlabelle]

• Explanation: Implements LSP 3.17.0's pull-model documentDiagnostics request, which fix stale squiggly issues after fixing an error due to the relationship between code in two files. When using pull-model documentDiagnostics, we disable the push-model publishDiagnostics to avoid reporting them twice.

• Scope: If the LSP client supports it, changes how diagnostics are transferred from a push- to a pull-model.
• Risk: LSP clients could report support for pull diagnostics without actually supporting it, which could lead to them not showing any diagnostics or outdated diagnostics. But I would consider that a bug in the LSP client.
• Testing: Added a unit test
• Issue: [SR-16080] SourceKit-LSP isn't aware of changes in other files #500 / rdar://95596860
• Reviewer: @ahoppen on Implement pull-model documentDiagnostics #746 and Add boilerplate for pull-model diagnostics #743

[MaxDesiatov]

@swift-ci test

[ahoppen]

@tristanlabelle Could you also include #743 in this PR?

[tristanlabelle]

My bad, here we go. @ahoppen

[ahoppen]

@swift-ci Please test

[ahoppen]

@swift-ci Please test Windows

[tristanlabelle]

Ok I see it won't be quite as simple as a cherry-pick. Looking into this

[tristanlabelle]

There was a bad merge. I pushed a fix. @ahoppen , could you help me with re-running the CI?

[MaxDesiatov]

@swift-ci test

[MaxDesiatov]

@swift-ci test windows

[MaxDesiatov]

@swift-ci test windows

[ahoppen]

@swift-ci Please test Windows

[tristanlabelle]

We're good to go!