Move TagHelperResolver to CodeAnalysis.Workspaces

- There's nothing specific about the TagHelperResolver that needs to be bound to VS. Moving it to the workspaces assembly so it can be used by VSCode.
- Also changed the `TagHelperResolver` to be an `IWorkspaceService`.
\n\nCommit migrated from 9f73afef3a

src/Razor/perf/Microsoft.AspNetCore.Razor.Performance/ProjectSystem/ProjectSnapshotManagerBenchmarkBase.cs

@@ -65,11 +65,11 @@ namespace Microsoft.AspNetCore.Razor.Performance
             var services = TestServices.Create(
                 new IWorkspaceService[]
                 {
+                    TagHelperResolver,
                     new StaticProjectSnapshotProjectEngineFactory(),
                 },
                 new ILanguageService[]
                 {
-                    TagHelperResolver,
                 });
 
             return new DefaultProjectSnapshotManager(