Camera: Add multi-resolution image reader and reprocessing support

- Add MultiResolutionImageReader class for variable size image output.
- Add camera characteristics for support multi-resolution output and input
streams.
- Update reprocessing interface doc for variable size support.

Test: atest MultiResolutionImageReaderTest, MultiResolutionReprocessCaptureTest
Bug: 156254356
Change-Id: I913abe38020c224c40903f42b8d45d40b65a5612