Add hardware feature android.hardware.camera.any.

This feature means that a device has at least one camera, facing in
some direction, so it matches devices that:
- Have just a back-facing camera
- Have just a front-facing camera
- Have both

In the future, it could also be used for devices that have a camera
that's neither front- or back-facing, such as a webcam or other
flexibly-pointed device.

Hidden for now.

Bug: 6847310
Change-Id: I51ea3b4db2020b0f056d77e10629a6b5f2daebe1