Android: Don't dismiss AdvancedMappingDialog when pressing Clear

If you already have a mapping set in the advanced mapping dialog and
want to change it, the easiest way to do it is to press Clear and then
select the new mapping from the list. But pressing Clear causes the
dialog to close, forcing you to open it again, which is inconvenient.
This commit makes it so the Clear button doesn't close the dialog.

Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/features/input/ui/AdvancedMappingDialog.kt

@@ -52,8 +52,9 @@ class AdvancedMappingDialog(
         selectDefaultDevice()
     }
 
-    val expression: String
+    var expression: String
         get() = binding.editExpression.text.toString()
+        set(value) = binding.editExpression.setText(value)
 
     override fun onItemClick(adapterView: AdapterView<*>?, view: View, position: Int, id: Long) =
         setSelectedDevice(devices[position])

Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/features/settings/ui/SettingsAdapter.kt

@@ -347,13 +347,15 @@ class SettingsAdapter(
         dialog.setButton(
             AlertDialog.BUTTON_NEUTRAL,
             context.getString(R.string.clear)
-        ) { _: DialogInterface?, _: Int ->
-            item.clearValue()
-            notifyItemChanged(position)
-            fragmentView.onSettingChanged()
-        }
+        ) { _: DialogInterface?, _: Int -> }
         dialog.setCanceledOnTouchOutside(false)
         dialog.show()
+
+        // We're setting this OnClickListener late so that pressing the Clear button won't result
+        // in the dialog closing
+        dialog.getButton(AlertDialog.BUTTON_NEUTRAL).setOnClickListener {
+            dialog.expression = ""
+        }
     }
 
     fun onFilePickerDirectoryClick(item: SettingsItem, position: Int) {