fix(language-service): Turn on strict mode for test project (#32783)

This is the last part in refactoring of the test project.
This PR turns on strict mode for typechecking and fixed tests that
fail under this mode.

PR Close #32783

packages/language-service/test/project/app/expression-cases.ts

@@ -44,5 +44,5 @@ export class ExpectNumericType {
   template: '{{ (name | lowercase).~{string-pipe}substring }}',
 })
 export class LowercasePipe {
-  name: string;
+  name: string = 'name';
 }