Refactor gradle configuration and update dependencies

- Enable java 11 language features
- Switch to groovy syntax
- Switch to new gradle plugins and dependency configuration
- Drop deprecated properties
- Switch from buildscript to project.ext closure for version property
- Update dependencies to latest stable versions
- Address build errors arising due to dependencies update

Signed-off-by: Aayush Gupta <aayushgupta219@gmail.com>

app/src/main/java/com/aurora/store/view/ui/commons/CategoryBrowseActivity.kt

@@ -109,6 +109,7 @@ class CategoryBrowseActivity : BaseActivity(), GenericCarouselController.Callbac
                 is ViewState.Success<*> -> {
                     updateController(it.data as StreamBundle)
                 }
+                else -> {}
             }
         })
 

app/src/main/java/com/aurora/store/view/ui/onboarding/AccentFragment.kt

@@ -169,7 +169,7 @@ class AccentFragment : BaseFragment() {
                 anim.duration = 450
                 anim.interpolator = CubicBezierInterpolator.EASE_IN_OUT_QUAD
                 anim.addListener(object : AnimatorListenerAdapter() {
-                    override fun onAnimationEnd(animation: Animator?) {
+                    override fun onAnimationEnd(animation: Animator) {
                         B.themeSwitchImage.setImageDrawable(null)
                         B.themeSwitchImage.hide()
                     }

app/src/main/java/com/aurora/store/view/ui/onboarding/ThemeFragment.kt

@@ -154,7 +154,7 @@ class ThemeFragment : BaseFragment() {
                 anim.duration = 450
                 anim.interpolator = CubicBezierInterpolator.EASE_IN_OUT_QUAD
                 anim.addListener(object : AnimatorListenerAdapter() {
-                    override fun onAnimationEnd(animation: Animator?) {
+                    override fun onAnimationEnd(animation: Animator) {
                         B.themeSwitchImage.setImageDrawable(null)
                         B.themeSwitchImage.hide()
                     }