Now they (A/B, non-A/B full and non-A/B incremental) share the same
code. Also add tests for the newly added function.
Test: python -m unittest test_ota_from_target_files
Test: Build A/B and non-A/B packages respectively.
Change-Id: I5499dd9c683ac1a18d8a24f21ff8845fe69f343e
Prior to this CL, we have similar codes in different paths
(WriteFullOTAPackage / WriteBlockIncrementalOTAPackage /
WriteABOTAPackageWithBrilloScript). This CL factors out the common codes
that deal with OEM-specific properties into BuildInfo class, and adds
tests for the new class.
Test: python -m unittest test_ota_from_target_files
Test: Create an incremental package that uses and doesn't use OEM
properties respectively.
Test: Create a full package that uses and doesn't use OEM properties
respectively.
Change-Id: Ida914cace12803d55396fa503bafcac2db2a520e
