camera: Add support for multiple camera capture requests

Camera capture requests need an extension to support multiple
physical cameras. Clients should be able to include the list
of additional physical camera ids as part of the request builder
call and then be able to modify them individually.

Test: Manual using camera application,
Camera CTS
Bug: 64691172

Change-Id: I280cb24b41076a2fb5603e91db30f060f7b53456