* (Android) Get rid of double bangs by using Kotlin view binding
Instead of holding a nullable reference to the WebView, we are now
accessing the WebView using the view binding utility of Kotlin's
Android Extensions.
Further reading:
https://kotlinlang.org/docs/tutorials/android-plugin.html
* (Android) Enable WebView debugging in debug builds
This enables debugging the app's WebView using Chrome's DevTools.
https://developers.google.com/web/tools/chrome-devtools/remote-debugging/webviews
* (Android) Make MainActivity.kt adhere to common Kotlin conventions
* (Android) Update dependencies and improve formatting of Gradle files
This updates the Kotlin plugin to 1.3.21 and the Gradle plugin to 3.3.2
* (Android) Remove unnecessary ConstraintLayout container
Layout files should generally have as few nested layers as possible,
because every layer affects the performance.
* (Android) Use JSONObject class to construct a JSON string
It is way safer to construct a JSON string using classes that are
meant for doing that, instead of concatenating raw strings.
* (Android) Suppress JavaScript lint warning
* (Android) Use Kotlin string templates instead of concatenating strings
* (Android) Add missing SuppressLint import
