The distinction between the inputs doesn't really make sense in the
mkShell context. Technically speaking, we should be using the
nativeBuildInputs most of the time.
So in order to make this function more beginner-friendly, add "packages"
as an attribute, that maps to nativeBuildInputs.
This commit also updates all the uses in nixpkgs.
Android is deprecating ndk.dir in favor of specifying exact NDK
version in Gradle configuration. Ensure that we can support multiple
NDKs, and link them into the location the Android Gradle Plugin expects.
androidenv did not previously write license files, which caused certain
gradle-based Android tools to fail. Restructure androidenv's list of
Android packages into a single repo.json file to prevent duplication
and enable us to extract the EULA texts, which we then hash with
builtins.hashString to produce the license files that Android gradle
tools look for.
Remove includeDocs and lldbVersions, as these have been removed
from the Android package repositories.
Improve documentation and examples.
