camera2: allow mixing regular/reprocess requests

Allow mixing regular and reprocess requests in burst requests.
Create RequestLastFrameNumbersHolder to store the last regular
frame number and the last reprocess frame number in a capture
request list which can be used to determine if the capture
sequence is completed.

Bug: 20537735
Change-Id: I0880f8c845380e1c7ffe504225a556829dfeccf6