Revert "Merge pull request #20558 from Pilchie/Fix19968-DuplicateSourceAndAdditionalFiles-DistinctIds"

This reverts commit 6f5b2d47, reversing
changes made to 66362df5.

This is a breaking API change.  Need to decide if we want to take it or
not.

moved cancellation to each InvokeAsync and use cancellation support provided by JsonRpc rather than cutting connections

now, it will get synched when remote host is first created rather than doing that on demand. so functionality change, so re-organized where things happening.

renamed CreateSession to TryCreateSession and added some doc comment.

Previously, when a VisualStudioWorkspace was constructed we were
doing a bunch of work in the constructor talking to the UI thread. This
was dangerous because we might get composed on a background thread.
This moves the dangerous initialization until we're creating a project
when we know we have a UI thread available.

In this refactoring I moved the project tracker and a few other fields
into a private class so it's more obvious what's dangerous to touch.
I also do a pass through all consumers of the property and either
update it to use the deferred state directly (because we're only
consuming projects, so it's fine if we don't have anything) or to the
factory method if we actually are creating projects.

This does temporarily regress the ability to create projects on
background threads, but it was unclear if that was generally safe to
start with.

this makes sending over roslyn-internal solution data to OOP from 3 minutes to 4 seconds.

after that, only changed assets are sent over which is usually less than 1-2ms.

this optimization is only for actually moving data between 2 processes. there are other things involved which need to be optimized as well to make whole system to be faster than right now (which takes about 1+ mins for initial solution load)

this will be used to improve perf

This reverts commit 720f5c5e, reversing
changes made to 6a6043c3.

added abstraction in remote host and diagnostic service to prevent VS.Next dll from loading if remote host option is off.

the abstraction I added here is specific to diagnostic service feature. that abstract solely exist to prevent VS.Next dll from loading if remote host option is off.

this is different than IHostSpecificService abstraction I used to have that is generalized form of this abstraction which automatically figure out what to load based on option and layering/MEF composition of roslyn.

in this model, each feature need to take care of this kind of issue.

changes include
make SourceText::GetChecksum and AnalyzerTelemetry contructor public.

added MustRunInProc in IBuiltInAnalyzer and some clean up around serializing Solution/Project/DocumentId and how DocumentState is exposed.

simplified temporary storage service's temporary storage management and added ability to attach to existing temporary storage

solution checksum and serialization service.

added remote host client
- this gives an ability for host (vs) to talk to remote host (service hub)

rename and moving files between feature/workspace layers
- only real change is having ICompilerDiagnosticAnalyzer interface which can either have inproc implementation or out of proc implementation.
- inproc is needed since diagnostics are in feature layer and one who uses feature layer out side of VS host need an implementation.

added RemoteWorkspace
- RemoteWorkspace has host agnostic implementation of roslyn features/services/workspace that will run in remote host

added service hub component and setup project for service hub
- service hub component is basically thin layer that deals with converting data to pass in to RemoteWorkspace

made devdiv insertion tool to ignore servicehub related files

support byte and char array natively in ObjectReader/Writer

this gives an ability for host (vs) to talk to remote host (service hub)