Pipe in Android camera and microphone [camera-role]

[jkaczman]

We need to figure out a way for the new camera-role functionality to reliably fetch the camera data and microphone data.

Ideally, we should be able to simultaneously stream H.264 and raw images as we do with rpicam-apps.

I imagine it might be easier to do this in native code since we're likely only to support Android for the near future.

Perhaps this issue should entail:

• Add native code to start a H.264 stream, fetch from that stream
• Add native code to fetch (ideally from something like the secondary stream we have) a raw image [thumbnail]
• Test this in a variety of conditions. What if the app is closed and re-opened? Does the phone overheat?
• How do we make this code applicable to a variety of Android phones? I imagine they have all kinds of different cameras. Not to mention, some may be on outdated Android versions.
• Should we detect when it's night-time in this code and turn on the flashlight?

Perhaps for the scope of this PR, we should separate this from the actual camera_hub/client_lib implementation (#94) to simplify review.