Camera3: Add flush support to HEIC composite streams

- Handle various corner cases with regard to REQUEST_ERROR, RESULT_ERROR, and BUFFER_ERROR.
- Drain the codec outputs in case the input buffer isn't dropped.
- Allow APP_SEGMENT to drop while still producing valid output image.
- Add a status tracker to manage active/idle state.
- Use frame number as key for pending input frames since with ZSL, 2
capture result could have the same timestamp.
- Also removed some deprecated variable/methods.

Test: CTS, vendor testing
Bug: 145579077
Change-Id: I9c3e929469b8fb75b32b016f9006036c954f663f