feat(ivy): accept multiple values for exportAs in the compiler (#28001)

exportAs in @Directive metadata supports multiple values, separated by
commas. Previously it was treated as a single value string.

This commit modifies the compiler to understand that exportAs is a
string[]. It stops short of carrying the multiple values through to the
runtime. Instead, it only emits the first one. A future commit will modify
the runtime to accept all the values.

PR Close #28001

packages/compiler/src/render3/view/t2_binder.ts

@@ -259,7 +259,10 @@ class DirectiveBinder<DirectiveT extends DirectiveMeta> implements Visitor {
         dirTarget = directives.find(dir => dir.isComponent) || null;
       } else {
         // This is a reference to a directive exported via exportAs. One should exist.
-        dirTarget = directives.find(dir => dir.exportAs === ref.value) || null;
+        dirTarget =
+            directives.find(
+                dir => dir.exportAs !== null && dir.exportAs.some(value => value === ref.value)) ||
+            null;
 
         // Check if a matching directive was found, and error if it wasn't.
         if (dirTarget === null) {