Accept proguard mapping file in resource shrinker

[mauriciogg]

Implementation of resource_shrinker cli. This is a direct copy pasta of the gradle resource shrinker https://cs.android.com/android-studio/platform/tools/base/+/mirror-goog-studio-main:build-system/shrinker/src/main/java/com/android/build/shrinker/ResourceShrinkerCli.java?q=ResourceShrinkerCli
With the addition of the --proguard_mapping in order to allow obfuscated builds to provide the obfuscation mapping to the resource shrinker.

This is half of the work needed to resolve #133
A follow up pr will wire the generated map by the r8 action to the srhinker action

[ahumesky]

since the original file is "Copyright (C) 2022 The Android Open Source Project" I think we may need to set up a third_party directory and maintain the original copyright header -- but this is actually more complicated than just adding a directory to this repo, because internally we have this code in a third_party directory, and we can't have a third_party directory within the third_party directory, so we'll have to figure out what to do here

[mauriciogg]

since the original file is "Copyright (C) 2022 The Android Open Source Project" I think we may need to set up a third_party directory and maintain the original copyright header -- but this is actually more complicated than just adding a directory to this repo, because internally we have this code in a third_party directory, and we can't have a third_party directory within the third_party directory, so we'll have to figure out what to do here

The flag is now available in R8 (https://partnerissuetracker.corp.google.com/issues/299961324). I think we can just wait for it to be released and remove the need for the custom tool