Absolutely no code actually persisted the data, so all the reading would always fail.

Rename intenral code to 'FindUsages' so it better reflects that it can present results for more than just FindReferences.

Our references were previously a mix of preview 4 and some build between preview 4 and 5.  That was causing build output double writes.

Fixes part 2 of #9674 for both the general code style page and the
naming style option page.

This also removes the superfluous "EnforcementLevel" class in the
NamingPreferences namespace that was basically a duplication of
"NotificationOption"/"NotificationOptionViewModel" in the general
CodeStyle namespace.

Fixes #12669. Addresses one part of #9674

Fixes both the general code styles page and the naming styles page

Use tuple syntax in the compiler

Create a code fix that offers to add a reference to System.ValueTuple if it is missing and you use a tuple.

* Hookup non-Roslyn view to the document tracking service on a foreground scheduled task.

RPS traces show that we are forcing the text view creation too eagerly on the UI thread during file open. This should very likely fix VSO #[223317](https://devdiv.visualstudio.com/DevDiv/_workitems?_a=edit&id=223317&triage=true).

* Explicitly schedule on a foreground task

We were using a Dictionary<..., Guid> which was forcing a JIT during
startup. Replacing it with Tuple<Guid> means we don't take the JIT
since it's a reference type.

These used to be split up into separate assemblies, but aren't anymore.

We were previously realizing the workspace and then reading in all the
FunctionIds to see if we should log each of those. We can do that from
the global option service directory (avoiding having to touch the
Workspace) and also not doing that until we actually need to. In most
cases ETW is off so we shouldn't even be looking at all.

This doesn't need to be initialized on the UI thread at all.