fix(ngcc): ensure that "inline exports" can be interpreted correctly (#39267)

Previously, inline exports of the form `exports.foo = <implementation>;` were
being interpreted (by the ngtsc `PartialInterpeter`) as `Reference` objects.
This is not what is desired since it prevents the value of the export
from being unpacked, such as when analyzing `NgModule` declarations:

```
exports.directives = [Directive1, Directive2];

@NgImport({declarations: [exports.directives]})
class AppModule {}
```

In this example the interpreter would think that `exports.directives`
was a reference rather than an array that needs to be unpacked.

This bug was picked up by the ngcc-validation repository. See
https://github.com/angular/ngcc-validation/pull/1990 and
https://circleci.com/gh/angular/ngcc-validation/17130

PR Close #39267

packages/compiler-cli/ngcc/src/host/commonjs_umd_utils.ts

@@ -264,3 +264,20 @@ export interface ExportsStatement extends ts.ExpressionStatement {
 export function isExportsStatement(stmt: ts.Node): stmt is ExportsStatement {
   return ts.isExpressionStatement(stmt) && isExportsAssignment(stmt.expression);
 }
+
+/**
+ * Find the far right hand side of a sequence of aliased assignements of the form
+ *
+ * ```
+ * exports.MyClass = alias1 = alias2 = <<declaration>>
+ * ```
+ *
+ * @param node the expression to parse
+ * @returns the original `node` or the far right expression of a series of assignments.
+ */
+export function skipAliases(node: ts.Expression): ts.Expression {
+  while (isAssignment(node)) {
+    node = node.right;
+  }
+  return node;
+}