update send feedback function name to match with js lib

Author: zoonooz

app/src/main/java/io/callstats/demo/csiortc/CsioRTC.kt

@@ -216,7 +216,7 @@ class CsioRTC(
    * Submit feedback of current call
    */
   fun sendFeedback(rating: Int, comment: String? = null) {
-    callstats.feedback(rating, comment)
+    callstats.sendUserFeedback(rating, comment)
   }
 
   // Peer connection

library/src/test/java/io/callstats/CallstatsTest.kt

@@ -158,7 +158,7 @@ class CallstatsTest {
 
   @Test
   fun feedbackSendValidEvent() {
-    callstats.feedback(3, "test", 1, 2, "remote1")
+    callstats.sendUserFeedback(3, "test", 1, 2, "remote1")
     verify(sender).send(argWhere {
       it is FeedbackEvent
           && it.feedback.comments == "test"