tv: hook up isFocused as observable property

This is kind of ridiculous, since the items own state should clearly be
queryable, but it doesn't appear to be the case here, so just shuffle it
around into kotlin and back.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

ui/src/main/java/com/wireguard/android/activity/TvMainActivity.kt

@@ -79,6 +79,10 @@ class TvMainActivity : AppCompatActivity() {
         binding.rowConfigurationHandler = object : ObservableKeyedRecyclerViewAdapter.RowConfigurationHandler<TvTunnelListItemBinding, ObservableTunnel> {
             override fun onConfigureRow(binding: TvTunnelListItemBinding, item: ObservableTunnel, position: Int) {
                 binding.isDeleting = isDeleting
+                binding.isFocused = ObservableBoolean()
+                binding.root.setOnFocusChangeListener { _, focused ->
+                    binding.isFocused?.set(focused)
+                }
                 binding.root.setOnClickListener {
                     lifecycleScope.launch {
                         if (isDeleting.get()) {