releasetools: Generate streamable A/B OTA packages.

In order to support streaming A/B OTA packages, we pack
payload_properties.txt and care_map.txt in ZIP_STORED mode. These two
entries along with payload.bin (already in ZIP_STORED prior to this CL)
can be fetched directly based on the offset and length info.

We write the offset and length info into the package metadata entry
(META-INF/com/android/metadata), which can be parsed by the OTA server.

payload_properties.txt and care_map.txt are usually less than 1-KiB. So
the change only incurs marginal size increase.

Bug: 33382114
Test: Generate an A/B OTA package. Verify the 'streaming-property-files'
      entry in the metadata file.

Change-Id: I04504e834eb36e18876c5f5a5a09289ee05c6f9a