CameraProvider release 6

Changes since version 5:

• Support another file picking API used by some apps (ACTION_PICK intents).
• Periodically cleanup old photos from storage.
• Support reading image orientation metadata from the content provider.
• Relicense under MPL 2.0.

CameraProvider release 5

Changes since version 4:

• First public release! 🎉
• Complete rewrite in Java without runtime dependencies.
• Decrease release apk size by about 75%.
• Fix rare crashes in old apps expecting extra metadata from the content provider.
• Add monochrome icon (currently it isn't shown on any surfaces in Android unfortunately).