update to new Transform API

[andrew-ld]

WARNING:API 'android.registerTransform' is obsolete.
It will be removed in version 8.0 of the Android Gradle plugin.
The Transform API is removed to improve build performance. Projects that use the
Transform API force the Android Gradle plugin to use a less optimized flow for the
build that can result in large regressions in build times. It’s also difficult to
use the Transform API and combine it with other Gradle features; the replacement
APIs aim to make it easier to extend the build without introducing performance or
correctness issues.

[axzae]

Use https://github.com/axzae/unmeta-gradle-plugin