Support multiple boot image profile aggregations in profman

Update the logic to be able to aggregate and operate on multiple
boot image profiles.

To assist with this change the flatten profile data will store
annotations as a list instead of a set. This way we can keep
track of how popular a method is across multiple profile (the
source packages can now be duplicated, in which case it means
that the same method was used in 2 different profiles by the
same package)

Test: gtests
Bug: 152574358
Change-Id: Iecb6891d0ebbaecc56acde8d8aae08dbfd91f61f
7 files changed