Implement a new bsdiff format

Add a new BSDF2 format that allows compression of ctrl/diff/extra streams
with different algorithms. The compression algorithm supported for now is
bz2 and brotli. This new format is similar to the legacy "BSDIFF40" format
except for the magic headers.

File format:
0       8    magic header
8       8    X
16      8    Y
24      8    new_file_size
32      X    compressed control block
32+X    Y    compressed diff block
32+X+Y  ???  compressed extra block

The magic header for BSDF2 format:
0 5 BSDF2
5 1 compressed type for control stream
6 1 compressed type for diff stream
7 1 compressed type for extra stream

Bug: 34220646
Test: unittest pass
Change-Id: I6eb0867e88476dbc4a4b7be609783f8c8a0a41cd