Merge dev15.7.x to dev15.8-preview2

Merge dev15.7.x to dev15.8-preview2

Merge dev15.7.x to dev15.8-preview2

Bump file version to 2.8.2

Revert "fix for CLR_EXCEPTION_System.NullReferenceException_80004003_Microsoft.VisualStudio.InteractiveWindow.dll (#26770)" (#26892)

This reverts commit db46bcf5.

See #26339 for the primary RCA.

This change corrects an additional edge case for ITextBuffer instances created before VisualStudioWorkspace attaches event handlers to ITextBufferFactoryService and IProjectionBufferFactoryService. This case is only believed to occur in IDE initialization scenarios where the workspace load is triggered by opening a document.

fix for CLR_EXCEPTION_System.NullReferenceException_80004003_Microsoft.VisualStudio.InteractiveWindow.dll (#26770)

Move Unshipped public APIs to Shipped

Desktop signing uses a COM call into the CLR to sign an assembly,
which is not available on Mono or CoreCLR. This change always
uses portable signing by default on Mono as well as CoreCLR.

"Generate method" refactoring enabled if method name is equal to imported type.

Use completion item InsertionText in the debugger, even before any non-debugger completion sessions have run

Exclude System.Net.Http from PortableFacades

`IAssemblySymbol.GivesAccessTo` now has a shared core implementation that permits operation across IAssemblySymbol implementations.
Fixes #26459
Fixes #26723
One remaining difference is in the treatment of a strong named assembly and a weak named assembly.  C# treats them as being (capable of being) related for error recovery.  VB does not. We would like to strengthen C# but that may be a breaking change, so we're leaving it as is, at least for now. (See also #26722)

Fixes #25829

Use appropriate analyzer category for these analyzers.

Escape curly braces in string literals when converting concatenation to interpolated string

Fix the message for Make Field Readonly

Naming style for locals

* Produce correct diagnostics on implicit operator conversions for stackalloc expressions

* PR Comments

Exclude Microsoft.Composition as something we build a dependency map for 

This creates ironically the reverse effect you might imagine:
CompilerExtension contains this package now, which would cause it to be
added to the dependency map; this then causes the package to be
excluded from the insertion package, where it is supposed to be. Since
CompilerExtension and VS are (in some sense) separate targets, presence
in the former shouldn't impact the other.

Fixes #26219

fix extension deployment and add explainatory comment

Add TaskExtensions to compiler package

Include missing facade: System.Diagnostics.DiagnosticSource