refactor(compiler-cli): expose TTC method to determine if file is tracked shim (#39768)

The Language Service "find references" currently uses the
`ngtypecheck.ts` suffix to determine if a file is a shim file. Instead,
a better API would be to expose a method in the template type checker
that does this verification so that the LS does not have to "know" about
the typecheck suffix. This also fixes an issue (albeit unlikely) whereby a file
in the user's program that _actually_ is named with the `ngtypecheck.ts`
suffix would have been interpreted as a shim file.

PR Close #39768

packages/compiler-cli/src/ngtsc/typecheck/api/checker.ts

@@ -7,6 +7,7 @@
  */
 
 import {AST, ParseError, TmplAstNode, TmplAstTemplate} from '@angular/compiler';
+import {AbsoluteFsPath} from '@angular/compiler-cli/src/ngtsc/file_system';
 import * as ts from 'typescript';
 
 import {FullTemplateMapping} from './api';
@@ -87,6 +88,12 @@ export interface TemplateTypeChecker {
    */
   generateAllTypeCheckBlocks(): void;
 
+  /**
+   * Returns `true` if the given file is in the record of known shims generated by the compiler,
+   * `false` if we cannot find the file in the shim records.
+   */
+  isTrackedTypeCheckFile(filePath: AbsoluteFsPath): boolean;
+
   /**
    * Retrieve the top-level node representing the TCB for the given component.
    *

packages/compiler-cli/src/ngtsc/typecheck/src/checker.ts

@@ -172,6 +172,10 @@ export class TemplateTypeCheckerImpl implements TemplateTypeChecker {
     return {nodes};
   }
 
+  isTrackedTypeCheckFile(filePath: AbsoluteFsPath): boolean {
+    return this.getFileAndShimRecordsForPath(filePath) !== null;
+  }
+
   private getFileAndShimRecordsForPath(shimPath: AbsoluteFsPath):
       {fileRecord: FileTypeCheckingData, shimRecord: ShimTypeCheckingData}|null {
     for (const fileRecord of this.state.values()) {

packages/language-service/ivy/references.ts

@@ -103,9 +103,7 @@ export class ReferenceBuilder {
 
     const entries: ts.ReferenceEntry[] = [];
     for (const ref of refs) {
-      // TODO(atscott): Determine if a file is a shim file in a more robust way and make the API
-      // available in an appropriate location.
-      if (ref.fileName.endsWith('ngtypecheck.ts')) {
+      if (this.ttc.isTrackedTypeCheckFile(absoluteFrom(ref.fileName))) {
         const entry = convertToTemplateReferenceEntry(ref, this.ttc);
         if (entry !== null) {
           entries.push(entry);