Update the Android SDK on Mac stacks

Description of the feature request

Current MacOs stacks don鈥檛 include the latest android sdk version (29) and build-tools (29.0.0 & 29.0.2). So it鈥檚 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: can't install sdk tools for android-29 路 Issue #57 路 bitrise-steplib/steps-install-missing-android-tools 路 GitHub).

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.