4512 Add link to CHANGELOG style in PR template (cla: yes, waiting for tree to go green)

4513 [camera] Fix version and CHANGELOG (cla: yes, p: camera)

4514 Enable Android integration tests in remaining plugins (cla: yes, waiting for tree to go green, p: camera, p: in_app_purchase, p: url_launcher, p: video_player, p: shared_preferences, platform-android)

4515 [url_launcher] Federate mobile implementations (cla: yes, p: url_launcher, platform-ios, platform-android)

4517 [in_app_purchase] Fix CHANGELOG for 0.2.0. (cla: yes, waiting for tree to go green, p: in_app_purchase, platform-ios)