this is to make develop - debug cycle easiler when adding new features to service hub.

to enable this, turn on Roslyn/FeatureManager/Features/RemoteHost and RemoteHostInProc

once enabled, InProcRemoteHostClient will be used instead of ServiceHubRemoteHostClient

except concrete type of RemoteHostClient, all other parts, exactly same code will be used.

InProcRemoteHostClient can be used in unit test to test client and server side as they are.

Adding size of unzipped roslyn extensions

make VS to send over initial assets in batch mode

* Handle irregular exits in perf cleanup

* address feedback

Repair missing code in lowering the decision tree.

Fix restore.cmd to handle repos with spaces

Fix for dropping of sideeffects in multiplication by 0

Expose CodeLens API to CodeLens, cleanup API

Added a case for Nullable<T>HasValue , which is also not sideeffecting fetch.

Disallow declaration of variables within constructor/field initializers.

* Make VS Project system components free threaded

1. DocumentProvider: DocumentProvider can now serve requests to open/close documents or register opened documents with project from background threads. Any operations that need foreground thread access (such as accessing RDT, VS Hierarchy, etc.) are scheduled on separate per-document tasks executed with the foreground task scheduler. Accesses to data structures that might be accessed from multiple threads are protected with locks.

2. VisualStudioProjectTracker: VisualStudioProjectTracker can now serve requests to add/remove projects, update binary paths used to track projects or notify workspace hosts of project state changes from background threads. Any operations that need foreground thread access are scheduled on the foreground task scheduler. Accesses to data structures that might be accessed from multiple threads are protected with locks.

3. AbstractProject: Similar to above, certain project system operations such add/remove of documents/references/analyzers, updating options, etc. can now be invoked from background threads.

Remove function that could was never called.

added some comments and refactored some code.

Fixes #13395

bump up OOP dependency versions to match preview 5

Directly read portions of string from metadata so we avoid intermediate allocations.

Delete some "catch (ArgumentException)"s that are extra suspicious

Prevent future backward compatibility issues around supporting deconstruction declaration as an out argument.

Related to #12597.

Prevent future backward compatibility issues around supporting deconstruction declaration as an out argument.

Fixes #13148.

Miscellaneous options cleanup