ARMeilleure: Implement single stepping (#3133)

* Decoder: Implement SingleInstruction decoder mode

* Translator: Implement Step

* DecoderMode: Rename Normal to MultipleBlocks

ARMeilleure/Decoders/DecoderMode.cs

@@ -0,0 +1,9 @@
+namespace ARMeilleure.Decoders
+{
+    enum DecoderMode
+    {
+        MultipleBlocks,
+        SingleBlock,
+        SingleInstruction,
+    }
+}