3127 [camera] Add null check before starting preview (cla: yes)

3129 [wifi_info_flutter] [wifi_info_flutter_platform_interface] Initial commit for wifi_info_flutter plugin and platform interface (cla: yes)

3130 Fix links in package example readmes (cla: yes)

3131 [image_picker] Update documentation to include information about support HEIC images. (cla: yes)

3132 [url_launcher] suppress a uses or overrides a deprecated API warning in WebViewActivity (cla: yes)

3134 [wifi_info_flutter_plugin_interface] implement wifi platform interface (cla: yes)

3135 [google_maps_flutter_platform_interface] Adds support for holes in polygon overlays to the Google Maps plugin (cla: yes, waiting for tree to go green)