3330 [path_provider_linux] Migrate to null safety (cla: yes, nnbd, p: path_provider, platform-linux)

3333 [url_launcher] Fix PlatformException introduced in nnbd release (cla: yes, nnbd, p: url_launcher)

3381 [ios_platform_images] Migrate to null safety (cla: yes, nnbd, p: ios_platform_images)

3398 [package_info] Migrate to null safety (cla: yes, nnbd, p: package_info)

3421 [quick_actions] Migrate to null safety (cla: yes, nnbd, p: quick_actions)

3423 [sensors] Migrate to null safety (cla: yes, nnbd, p: sensors)