Update example Android apps toolchain (AGP 3.5.0, AndroidX)

[elizarov]

• Gradle 5.4.1
• AGP 3.5.0
• Migrated to AndroidX
• Updated versions of all dependencies to the most recent ones
• Removed proguard rules

[KaiyuanZhao]

hi @elizarov
ui/kotlinx-coroutines-android/build.gradle is still using com.android.support:support-annotations:$android_support_version

[elizarov]

@KaiyuanZhao what should it use instead?

[KaiyuanZhao]

@elizarov use androidx.annotation:annotation instead of support. This is the full mapping

[elizarov]

Tried it. Cannot find androidx.annotation:annotation artifact in any of the repositories we are using in our build (including a google repo).

[KaiyuanZhao]

@elizarov Did you add version after annotation? The full dependency notation is androidx.annotation:annotation:1.1.0

[KaiyuanZhao]

@elizarov Androidx annotation document is in this link. And this artifact is in google repo.

[elizarov]

Thanks. See #1932