Enable analyzers on Roslyn.sln except for two very slow ones

Add Shared attributes to code fix providers

Offer to not generate fields when generating a new constructor.

Add feature to convert from ReferenceEquals to 'is null'

Update Integration tests utility to support Unload/Reload project and nuget restore

Throw early if an invalid buffer is passed to ISuggestedActionsSource

The inherited "Warning" severity will result in error reports on CI builds
due to the use of TreatWarningsAsErrors.

Launch settings for test projects

Disable analyzers on developer builds

Use ConfigureAwait

Restructure how assets are published

A recent change to enable analyzers caused a 3-6X build slow down.
Disabling them locally at least until we can track this down.

https://github.com/dotnet/roslyn/issues/21041

Update Debugger nuspecs

Be resilient to getting back no spans to tag.

[Test failure] BasicExpressionEvaluator: COMException : Operation not supported. Unknown error: 0x8971003c  (#21037)

In integration tests, verify that we send telemetry

Fixes https://github.com/dotnet/roslyn/issues/20105

Re-enable analyzers in the master branch

Fix crash with F# project references

Move to newer version of Microsoft.Net.Compilers and Microsoft.NetCore.Compilers compatible with latest analyzers package

If you had a F# project opened with the new project system, it'd supply
an output directory which other projects (like C#) could reference.
If you had a C# project that referenced the F# project, any attempt
to get the C# compilation would crash because we can't actually produce
F# compilations. The fix is simple: don't convert from metadata
references.

If we're going to require it, let's at least crash with a useful
exception instead of a null ref.

Other components should be able to access this too, especially since
the workspace itself isn't always there.

Preserve leading directives when removing an unused variable.

Merge dev15.3.x to master

# Conflicts:
#	build/Targets/Versions.props
#	src/VisualStudio/Core/Test.Next/VisualStudioTest.Next.csproj
#	src/Workspaces/CoreTest/ServicesTest.csproj
#	src/Workspaces/CoreTestUtilities/WorkspacesTestUtilities.csproj