Add ts-no-import-ext flag (#7748)

Co-authored-by: Derek Bailey <derekbailey@google.com>

tests/ts/tsconfig.json

@@ -21,6 +21,7 @@
     "optional_scalars/**/*.ts",
     "namespace_test/**/*.ts",
     "union_vector/**/*.ts",
-    "arrays_test_complex/**/*.ts"
+    "arrays_test_complex/**/*.ts",
+    "no_import_ext/**/*.ts"
   ]
 }