Remaining issues for "sync namespace" refactoring

Using this to track some of the remaining issues for the "Sync namespace" refactoring.

[ ] Fix undo of move file
[x] Make this refactoring work on CPS based projects (#30998, https://github.com/dotnet/project-system/pull/4312)
[ ] Change of default namespace through Project Properties page is not reflected in workspace. Need to figure out how to listen to that change.
[ ] Provide move file operation for CPS, also applies to move type refactoring. (blocked by https://github.com/dotnet/project-system/issues/3425)
[ ] Change namespace from global to non-global, the fix reference like global:Foo. (including cref)
[ ] Use IProgressTracker https://github.com/dotnet/roslyn/pull/30156#discussion_r230469406
[ ] Unification of C# and VB logic
[x] Refactor into Change namespace service (#31447 ) and move file service (this also covers move type refactoring). Related to #30896
[ ] Fix tests to avoid leak of implementation details https://github.com/dotnet/roslyn/pull/30156#discussion_r230452271
[ ] Offer refactoring at pos-0? https://github.com/dotnet/roslyn/pull/30156#discussion_r230455424
[ ] Minor change to reduce redundant computation https://github.com/dotnet/roslyn/pull/30156#discussion_r230470934
[ ] Find-all-ref w/o cascading (perf improvement) https://github.com/dotnet/roslyn/issues/25628
[ ] Behavior of addimport service https://github.com/dotnet/roslyn/pull/30156#discussion_r230477008
[ ] Integration test for VS workspace behavior and undo
[ ] #34707

dotnet / roslyn