Bug: ProguardMapping is not queryable nor deterministically generated

[EdbertChan]

There is a bug in rules_android where the proguard_mapping file may not be reproduced. The root cause is that the proguard mapping file is not being explicitly declared as the output of the implicit target.

Reproduction steps:

1. Build a Bazel binary that enables proguard mapping, enables disk, and remote cache
2. Run bazel clean --expunge
3. Rebuild the Bazel binary.
4. Observe the proguard mapping is not found at bazel-out/xplat-fastbuild/bin//_RESOURCES_DO_NOT_USE_proguard.map

Furthermore, there is no way to actually query this file. This is problematic because we will need to upload the obfuscated mapping when debugging/deobfuscating builds.

bazel cquery //:_RESOURCES_DO_NOT_USE --output files

[ahumesky]

is proguard_generate_mapping enabled on the android_binary? https://bazel.build/reference/be/android#android_binary.proguard_generate_mapping

the proguard mapping file should be an implicit output of the binary, available as targetname_proguard.map

https://bazel.build/reference/be/android#android_binary_implicit_outputs