[3.14] gh-146450: Normalise feature set of Android build script with other platform build scripts (GH-146451) (#148065)

Allows for cleaning a subset of targets, customization of the download cache and
cross-build directories, and modifies the build command to allow 'all', 'build'
and 'hosts' targets.
(cherry picked from commit b8470deb5d52f524ae18c6f232fecfc99b133397)

Co-authored-by: Russell Keith-Magee <russell@keith-magee.com>