Implement audio backend configuration option (#1325)

* Implement audio backend configuration option

* Use OpenAL by default

* Increment version number in config.json

and add 30px to the height of the settings window

* nits

* capitalise audio backend names

Ryujinx.Common/Configuration/ConfigurationFileFormat.cs

@@ -13,7 +13,7 @@ namespace Ryujinx.Configuration
         /// <summary>
         /// The current version of the file format
         /// </summary>
-        public const int CurrentVersion = 9;
+        public const int CurrentVersion = 10;
 
         public int Version { get; set; }
 
@@ -127,6 +127,11 @@ namespace Ryujinx.Configuration
         /// </summary>
         public int FsGlobalAccessLogMode { get; set; }
 
+        /// <summary>
+        /// The selected audio backend
+        /// </summary>
+        public AudioBackend AudioBackend { get; set; }
+
         /// <summary>
         /// Enable or disable ignoring missing services
         /// </summary>