Dependencies tree refactor

[kvenkatrajan]

Summary

This is a placeholder task to refactor the current dependency tree implementation within .NET Project System. This would be a prerequisite to AB#1503715 and AB#1781382

User Impact

This is an effort to make the make the dependencies tree more maintainable and reliable for supporting multi targeting and configuration switch scenarios in terms of UI display. Documentation will be added as a part of the refactor

[drewnoakes]

Issues I'm hoping to address as part of this work:

Core fixes:

• Use Dataflow and snapshots for dependencies node data processing #6183
• Dependency node does not handle configuration switches #3642
• Request new dependency tree icons from the design team #8946
• Unresolved packages/projects should show errors in dependency tree #8947
• DependenciesSnapshotProvider is marked with [ProjectAutoLoad] with a dynamic capability #5519
• Provide feedback that dependencies node is populating #5045
• Don't show dependency warning icons while waiting for design-time build #5044
• Remove concept of "short name" in TargetFramework #2795
• When changing a package version, update rather than replace the tree node #8998

Probable fixes:

• Dependencies node fails to handle custom target frameworks #2618
• Dependencies tree should appear populated when the project first appears in Solution Explorer #8949
• Transitive dependency items not attached for all target frameworks when multi-targeting #6832
• Roslyn is unable to add diagnostic nodes properly in multi-targeting projects #6820
• Multiple equivalent target framework short names cause exception #6203
• Inefficient way to create the first version of the dependencies tree after loading a project #3321
• Perf: DependenciesTree UpdateTree logic (BuildTreeForSnapshotAsync) is way too expensive #2707
• Dependencies node fails to handle custom target frameworks #2618
• Dependency node doesn't handle Multi-targeting with a multi portable frameworks  #2524

Stretch goals (even if not met, this work contributes to these):

• Dependency node has warning icon when you reference the same reference twice #6668
• Make the Dependency Tree general purpose for all languages #6594
• Add an API that lets consumers wait on dependency node to be up-to-date with a given project version #3426
• TargetFramework fails to differentiate by NuGet profile name #2617
• Remove all concepts of "target framework" and that configurations are driven from them #2525

[drewnoakes]

PR is up for this work: #9008

An additional PR against NuGet.Client fixes a few more issues: NuGet/NuGet.Client#5146