A fork of cargo2android, initially aimed at big imports like crosvm.
* Faster run time when there are many packages (30 min -> 1 min for
crosvm).
* `--reuse-cargo-out` feature allows iterating on most of the config
with sub second run time.
* Most options can be specified per-package.
Bug: 261486161
Test: ran on crosvm and checked diffs
Change-Id: Iaf3f4732e828a6f8b281f0e63fe1e0e1e9e98631