Fixes #10132

Adds a map from ISymbol (assembly or module symbols) to ProjectId so we can find projects for skeleton assemblies even after its compilation could have been GC'd.

This brought along some references to Microsoft.VisualStudio.Threading
that we previously didn't have. Nothing was wrong with this, but it
meant I had to fix some namespace qualifications that were assuming the
"Threading" namespace was unambiguous.

These keep coming back.

To prevent projects across the tree from having different dependencies, we unify
external package dependencies by creating empty C# projects that represent them.
We then make use of project.json package inheritance (where a project inherits
all packages dependencies from their dependencies) to unify it across the tree.

No projects outside of this tree, should be directly referencing versions of
these dependencies manually.

For this check-in I've tackled Metadata, Reflection, and DiaSymReader. Will tackle
the rest in future commits.

In turns out that the behavior of "Go to previous member" in VB was actually
to go to the start of the current member if you weren't already at the start.
Support that again.

Fixes #10588

the race happened since we cleared _state before pending background work is all finished.

now we correctly capture state so that right state is passed around.

added flag for including project non local result.

make analyzer driver won't get into action execution when there is actually no action for the analyzer

VB: Always import instance fields for an Enum type in order to be able to infer underlying type of its elements.

Address https://devdiv.visualstudio.com/DefaultCollection/DevDiv/_workitems?_a=edit&id=193333.

Earlier the perf test runner using CPC was broken. This change fixes that.

With this change, we will be running CPC a little different than what we used to.
Earlier, we run CPC for 'n' of iterations and the first iteration should to be a
warmup iteration. Each iteration runs all the tests once.

Now, we run CPC for 'n' iterations for each test and 'n' is defined by each test.
The first iteration is, again, a warmup iteration and the rest are considered for the
metrics calculation. With this model, each iteration will run just one test instead of
running all the tests in an iteration. This helps in making the warmup iteration, a
true warmup iteration.

Minor changes:
Since the test csx returns an object now, the test related information has been
moved to the corresponding test csx files.

Simplest fix for this issue to be considered for Micro-Update

added assert for GetEffectiveDiagnostics

removed unnecessary GetEffectiveDiagnostics call for diagnostics from CompilationWithAnalyzers and other code clean up.

added some comments, code clean up and rename.

changed test to use GetDiagnosticsAsync rather than GetProjectDiagnosticsAsync

Move to a non-fatal-watson so we can get enough information to figure out why we're getting invalid data back from SyntaxTreeInfo.