Fix control event String parsing

At least 2 bytes must be available to read the length of the String.

server/src/main/java/com/genymobile/scrcpy/ControlEventReader.java

@@ -93,7 +93,7 @@ public class ControlEventReader {
     }
 
     private ControlEvent parseTextControlEvent() {
-        if (buffer.remaining() < 1) {
+        if (buffer.remaining() < 2) {
             return null;
         }
         int len = toUnsigned(buffer.getShort());