fix(compiler-cli): do not add references to files outside of rootDir (#19770)

References to resources (such as .css files) that are generated into
the `outDir` directory outside of `rootDir` would cause a spurious
compiler error about not being able to find a files that ends in
'.ngstyle.ts'.

Also fixed a minor issue in compiler error reporting

Fixes: #19765, #19767

PR Close #19770

packages/compiler-cli/test/transformers/compiler_host_spec.ts

@@ -252,10 +252,10 @@ describe('NgCompilerHost', () => {
     it('should clear old generated references if the original host cached them', () => {
       codeGenerator.findGeneratedFileNames.and.returnValue(['/tmp/src/index.ngfactory.ts']);
 
-      const ngHost = createNgHost();
       const sfText = `
           /// <reference path="main.ts"/>
       `;
+      const ngHost = createNgHost({files: {'tmp': {'src': {'index.ts': sfText}}}});
       const sf = ts.createSourceFile('/tmp/src/index.ts', sfText, ts.ScriptTarget.Latest);
       ngHost.getSourceFile = () => sf;