mixins: Add FriendAdded event

* added onAddedFriend() event

* renamed events to FriendAdded and FriendRemoved

runelite-api/src/main/java/net/runelite/api/events/FriendAdded.java

@@ -0,0 +1,15 @@
+package net.runelite.api.events;
+
+import lombok.Value;
+
+/**
+ * An event where a request to add a friend is sent to the server.
+ */
+@Value
+public class FriendAdded
+{
+	/**
+	 * The name of the added friend.
+	 */
+	private final String name;
+}

runelite-api/src/main/java/net/runelite/api/events/FriendRemoved.java

@@ -30,7 +30,7 @@ import lombok.Value;
  * An event where a request to remove a friend is sent to the server.
  */
 @Value
-public class RemovedFriend
+public class FriendRemoved
 {
 	/**
 	 * The name of the removed friend.