In the new SDK we no longer have a need for ProjectGuid. This change
will:

- Remove ProjectGuid from project files
- Remove Name + Project items from ProjectReference entries
- Change BuildBoss to enforce both of these items

It is possible that a reference to Nuget.VisualStudio.dll will not be found during /t:clean builds (looks like the ResolvePackageDependenciesForBuild target skips resolution of nuget references during such builds). In such cases, rather than reporting an error, we will simply skip embedding the PIA.

The MarkNuGetVisualStudioPackageWithEmbedInteropType target was depending on a ResolveNuGetPackageAssets target that no longer runs as part of Roslyn builds since Roslyn has been switched over to use the new SDK. Consequently, the Nuget.VisualStudio PIA was not getting embedded in MicroSoft.VisualStudio.LanguageServices.dll. Switching the dependency to the ResolvePackageDependenciesForBuild target should fix this issue.

Revert "Merge pull request #20558 from Pilchie/Fix19968-DuplicateSourceAndAdditionalFiles-DistinctIds"

This reverts commit 6f5b2d47, reversing
changes made to 66362df5.

Fixes crashes associated with InvisibleEditor

Move IVsSQM.cs to VS where it was being used as a linked file.

Fixes #20599

This is a breaking API change.  Need to decide if we want to take it or
not.

Turns out we could end up with the same IVisualStudioHostDocument
for both, if they are both added.

Fixes #19968.

ThemeColorFixers was running during ASL for some users and forcing the editor to compose at that time. Instead, we wait until a text editor of the appropriate content type has been opened.

Addresses devdiv bug https://devdiv.visualstudio.com/DevDiv/_workitems/edit/130129

Migrated the remainder of our code base to use the new SDK via the
ConvertPackageRef tool.

https://github.com/jaredpar/ConvertPackageRef