android: Add additional check for hasMapping

Controls can have no mapping if they are either "[empty]" or and empty string. This was causing an issue if you reset mapping on all controllers and then tried to play a game. The check to determine whether auto mapping was required would fail and leave you will no mapped controllers. This feels a bit like user error but it smooths things out if you forget so I see it as necessary.

src/android/app/src/main/java/org/yuzu/yuzu_emu/features/input/model/PlayerInput.kt

@@ -64,17 +64,17 @@ data class PlayerInput(
     fun hasMapping(): Boolean {
         var hasMapping = false
         buttons.forEach {
-            if (it != "[empty]") {
+            if (it != "[empty]" && it.isNotEmpty()) {
                 hasMapping = true
             }
         }
         analogs.forEach {
-            if (it != "[empty]") {
+            if (it != "[empty]" && it.isNotEmpty()) {
                 hasMapping = true
             }
         }
         motions.forEach {
-            if (it != "[empty]") {
+            if (it != "[empty]" && it.isNotEmpty()) {
                 hasMapping = true
             }
         }