Update version for 16.7 Preview6

Backport 45942 to dev16.7.  Include information why symbol key resolution has failed to help with debugging

Skip HighlightRefsMultipleSubmisionsVerifyRenameTags tests

(cherry picked from commit 63a730bb)

Remove reference to non-existing VisualStudioInteractiveComponents.vsix from deployment VSIX. (#45979)

Fixes Roslyn preview installer.

Add VisualStudio2019.pkgdef to the Roslyn package

Update Version for preview 5.

Change signature accessibility - add screenreader header for empty column

Mark apis as shipped

Avoid SoftCrashException from CodeLens data point invalidation calls

(16.7) Reduce release/x64 baseline in DeeplyNestedGeneric

[LSP] Remove snippets from completion list until they are supported

Allow independent methods to have the same parameter name

Change Signature: Fix for NullReferenceException when trying to add parameter with type modifier

Revert "Move SymbolSearch down to EditorFeatures (#45505)"

Inline rename highlight color in Dark Theme only has a contrast ratio of 1.238:1, and the target is 1.5:1

Original Color: #A6F1A6
New Color: #D3F8D3

Contrast ratio is 1.485:1 with new color

Resolves: https://devdiv.visualstudio.com/DevDiv/_workitems/edit/1139737

This reverts commit f755e8a8. That
change meant our EditorFeatures code was using DllImports in the
cross-platform binary, and we weren't sure what that would do in
VS for Mac if that code ran. It also brought a dependency on
Microsoft.VisualStudio.RemoteControl, which also seems to depend on
various Windows specific APIs.

We'll finish up the decision of what to do in
https://github.com/dotnet/roslyn/pull/45115

Prevent trying to convert metadata references into circular project references

Co-authored-by: NAlekseyTs <AlekseyTs@users.noreply.github.com>

If you have two projects that reference each other with metadata
references, we should avoid converting both of them into project
references as that causes a circularity in the Workspace layer.
The workspace API correctly throws exceptions if you try to do this,
but the Visual Studio project system layer wasn't checking, and so it'd
call into the Workspace APIs and throw exceptions. Unfortunately this
often resulted in us getting into corrupted states where the data
structures got out of sync, which might later result in other exceptions
too.

This fix isn't entirely correct in that we're not going to re-convert
the metadata reference to the project reference if something else breaks
the circularity; that's better than crashing so this is an improvement
either way.

Fixes https://github.com/dotnet/roslyn/issues/39904
Fixes https://github.com/dotnet/roslyn/issues/43633