Georg Koppen authored Nov 24, 2020 and Matthew Finkel committed Dec 12, 2020

Gradle versions change more frequently compared to other toolchain
parts. We don't want to rebuild the whole toolchain and subsequently all
projects just because the Gradle version for one project has changed.
We therefore start with creating an own, separate Gradle project where
all the respective Gradle versions needed by different projects are
fetched and prepared.

Gradle versions still present in `android-toolchain` will move over to
this new project in later commits.

We start with Gradle 6.5 as that is used for `application-services` now.