android: Pair fastmem toggle to CPU Debug toggle

Hides fastmem toggle when CPU Debugging is disabled

src/android/app/src/main/java/org/yuzu/yuzu_emu/features/settings/model/view/SettingsItem.kt

@@ -298,6 +298,7 @@ abstract class SettingsItem(
 
                 override val key: String = FASTMEM_COMBINED
                 override val isRuntimeModifiable: Boolean = false
+                override val pairedSettingKey = BooleanSetting.CPU_DEBUG_MODE.key
                 override val defaultValue: Boolean = true
                 override val isSwitchable: Boolean = true
                 override var global: Boolean