Add ability to collapse XML comments to short/compact collapsed form.

[fiseni]

Fixes #126

I reused the same infrastructure of the attribute collapse tagger. Changes include:

• Added common abstract collapse tagger
• Added CollapseXmlCommentTagger
• Refactored the CollapseAttributeTagger.
• Some of the NuGet dependencies were no longer available, so all NuGet packages for Tweakster2022 are updated to the latest versions. Tweakster2019 is left as is.

PS. There are also version conflicts, binding redirects might need to be added. Not added as part of this PR.

[fiseni]

@madskristensen Not ready for merging.
It seems the built-in tagger suppresses the custom one. Any tip here would be appreciated.