Remove IPersistentStorageService, ITemporaryStorageService, ITemporaryTextStorage and ITemporaryStreamStorage.

[CyrusNajmabadi]

These APIs existed to provide access to Roslyn's "DB" index service and "Memory Mapped File" service.

Both were Obsoleted and made into no-op services 2 years ago with #56912 and #62998. Any code attemping to recompile against them already errors. And any code that still uses them gets no-op services that fail on every operation you try (in other words, writing/reading to the DB doesn't actually work) and attemping to write/read to memory mapped files also just no-ops).

Roslyn still has internal versions of these APIs. We intend to continue using the DB api (as that is still very useful for persisting data between vs sessions). However, we are intending on removing hte memory-mapped-file api as that only existed for us to workaround VM limitations imposed by VS being 32bit.

Now that enough time has passed, and that these apis literally do nothing, we can/should remove them.

[333fred]

API Review

• Is there any benefit to removing them?
  • Could just mark them EditorBrowsable.Never?
  • Doesn't cost us anything to keep?
  • Might be useful for us to ensure that we're actually moving off of these 32-bit apis
• Bring it up with the compat council
  • Are we able to look at the marketplace and see if we actually have users of this API?
  • Should we put in telemetry?

Needs work. Will work with compat council to clarify our policy here.

[CyrusNajmabadi]

Nothing in grep.app. Talking to @jaredpar about additional tools to look for usage anywhere.