Update the Android SDK on Mac stacks

Description of the feature request

Current MacOs stacks don’t include the latest android sdk version (29) and build-tools (29.0.0 & 29.0.2). So it’s impossible to build on those stacks when targeting the last sdk version.

Use case / for what or how I would use it

The Install missing android tools fail to download the new tools in this case (see this PR on Github for more information: https://github.com/bitrise-steplib/steps-install-missing-android-tools/issues/57).

So the only option left is to have it already installed on MacOs stacks

Thanks for the #feature-request @le.flow! This solution would also definitely make sense, we are looking into both options.