Make system property audio.camerasound.force a vendor-writable property,

This property is read by the audio service in system server to toggle
camera shutter sound enforcement on a device-specific basis.

Test: Camera shutter sound enforcement works when audio.camerasound.force is set
Bug: 110126976
Change-Id: I2720d3c699c4712d1a328f59dde0b16bbf1016f3