4107 [flutter_plugin_tools] Move license-check tests to runCapturingPrint (cla: yes, waiting for tree to go green)

4108 Add Basic Junit Tests to some plugins (cla: yes, p: webview_flutter, p: google_sign_in, p: local_auth, p: video_player, p: shared_preferences, platform-android)

4109 [flutter_plugin_tools] release 0.3.0 (cla: yes)

4110 [flutter_plugin_tools] ignore flutter_plugin_tools when publishing (cla: yes, waiting for tree to go green)

4111 [flutter_plugin_tools] Restructure version-check (cla: yes)

4112 Split some Cirrus script steps (cla: yes)