Adding new packages to the first-party package issue template (#138540)

Closes https://github.com/flutter/flutter/issues/138539.

Adding `two_dimensional_scrollables`, `process`, `platform` to the first-party package issue template so user can file issues related to them.

.github/ISSUE_TEMPLATE/9_first_party_packages.yml

@@ -59,12 +59,15 @@ body:
         - palette_generator
         - path_provider
         - pigeon
+        - platform
         - plugin_platform_interface
         - pointer_interceptor
+        - process
         - quick_actions
         - rfw
         - shared_preferences
         - standard_message_codec
+        - two_dimensional_scrollables
         - url_launcher
         - video_player
         - web_benchmarks