Collect new Android soong "METADATA" and related package metadata

[pombredanne]

See https://android.googlesource.com/platform/external/bpftool/+/refs/heads/master/METADATA or https://android.googlesource.com/platform/external/fmtlib/+/refs/heads/master/METADATA or https://github.com/thka2016/lpunpack_and_lpmake_cmake/blob/fa425557ba311780261db911977123d45571ec5f/lib/zlib/METADATA#L2

This format is neither YAML, nor JSON nor Python, but resembles each of these.

There are other formats like the .bp files https://android.googlesource.com/platform/build/soong/+/refs/heads/master/provenance/Android.bp#18 used by soong (bp is formerly for the now dead blueprint build tool)

Note that this is on the latest Android build tool (soong) and is not present consistently in all external libraries.

See https://android.googlesource.com/platform/build/soong/+/refs/heads/master/compliance/ for code that creates and process these.

See also:

• https://android.googlesource.com/platform/build/soong/+/refs/heads/master/licenses/
• https://github.com/aosp-mirror/platform_development/blob/master/scripts/add3prf.py and https://github.com/aosp-mirror/platform_development/blob/master/scripts/add3prf_test.py

This may be similar to the BUCK METADATA format