Refactor update_verifier into a class

The refactor separates out the parsing of care_map and the actual
verification of the partitions. Moreover, it skips the verification in case
of a format error in the care map.

Also, the parsing of care_map now uses the suffix of the file to
tell if it has the protobuf format or the plain text format.

Bug: 115740187
Test: unit test pass
Change-Id: I7aa32004db02af1deb7bfdc6f5bd7921eb7883e5