fix(ivy): use default selector for Components if selector is empty (#29239)

Prior to this change default selector for Components was not applied in case selector is missing or defined as an empty string. This update aligns this behavior between Ivy and VE: now default selector is used for Components when it's needed. Directives with empty selector are not allowed and trigger a compile-time error in both Ivy and VE.

PR Close #29239

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

@@ -172,7 +172,8 @@ export function extractDirectiveMetadata(
       throw new FatalDiagnosticError(
           ErrorCode.VALUE_HAS_WRONG_TYPE, expr, `selector must be a string`);
     }
-    selector = resolved;
+    // use default selector in case selector is an empty string
+    selector = resolved === '' ? defaultSelector : resolved;
   }
   if (!selector) {
     throw new Error(`Directive ${clazz.name !.text} has no selector, please add it!`);