Bump to Kotlin 1.4.20 and bump Android Gradle Plugin to 4.1.0

[dazza5000]

No description provided.

[kpgalligan]

Thanks for the PR. Intellij doesn't like this version of the AGP yet, so waiting on that.

[brady-aiello]

Tried this today, and still no dice on Intellij working w/ AGP. It's fixed in code (https://youtrack.jetbrains.com/issue/IDEA-252775), but it just missed the cutoff for 2020.3. So it'll be in 2021.1, whenever that comes out, and it's probably available in the EAP, but they don't list it on the landing page https://www.jetbrains.com/idea/nextversion/#section=mac

[brady-aiello]

Whenever 2021.1 comes out and we can merge this, we'll also need to rename this AGP config parameter:

The Kotlin DSL compile option coreLibraryDesugaringEnabled has been changed to isCoreLibraryDesugaringEnabled.

Release notes: https://developer.android.com/studio/releases/gradle-plugin?authuser=1#4.1-dsl-desugaring

And then we should be good to go.

[brady-aiello]

We've updated Kotlin and AGP a few PR's ago. Sorry for the delay.