Adding showcase as debugImplementation breaks the release build

[Kshitij09]

When we add showcase dependency as mentioned in the README

debugImplementation "com.airbnb.android:showkase:1.0.3"

and we would want to assign click action to launch showkase browser activity only in the debug build, current setup breaks the release build as the object Showkase won't be available.

We can either create no-op showcase module for releaseImplementation or split the code between debug & release source sets to make above dependency as implementation. Happy to raise a PR with suitable approach!