refactor(compiler): synthesize external template node for partial compilation (#40237)

When partially compiling a component with an external template, we must
synthesize a new AST node for the string literal that holds the contents of
the external template, since we want to source-map this expression directly
back to the original external template file.

PR Close #40237

packages/compiler-cli/src/ngtsc/annotations/src/component.ts

@@ -958,14 +958,6 @@ function sourceMapUrl(resourceUrl: string): string {
  * some of which might be useful for re-parsing the template with different options.
  */
 export interface ParsedComponentTemplate extends ParsedTemplate {
-  /**
-   * A full path to the file which contains the template.
-   *
-   * This can be either the original .ts file if the template is inline, or the .html file if an
-   * external file was used.
-   */
-  templateUrl: string;
-
   /**
    * True if the original template was stored inline;
    * False if the template was in an external file.