Find references of a module by filename (#41805)

* Naive implementation enough to build and write a test

* Add simple test

* Add project references test

* Add deduplication test, accept baselines

* Add test for referencing a script (doesn’t do anything)

* Update API baselines

* Use refFileMap for non-module references

* Fix find-all-refs on module specifier

* Remove unused util

* Don’t store text range on ts.RefFile

* Ensure string literal could itself be a file reference

* Remove unused utilities

* Improve baseline format

* Preserve old behavior of falling back to string literal references

* Update baselines from master

* Fix old RefFileMap code after merge

* Add test for additional response info

* Undo test change

src/harness/harnessLanguageService.ts

@@ -519,6 +519,9 @@ namespace Harness.LanguageService {
         findReferences(fileName: string, position: number): ts.ReferencedSymbol[] {
             return unwrapJSONCallResult(this.shim.findReferences(fileName, position));
         }
+        getFileReferences(fileName: string): ts.ReferenceEntry[] {
+            return unwrapJSONCallResult(this.shim.getFileReferences(fileName));
+        }
         getOccurrencesAtPosition(fileName: string, position: number): ts.ReferenceEntry[] {
             return unwrapJSONCallResult(this.shim.getOccurrencesAtPosition(fileName, position));
         }