Improve quickfix to replace += operator with StringBuilder on left hand side with append() call

now works on java.lang.Appendable and splits concatenated strings into separate append calls

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/changeToAppend/before2.java

@@ -0,0 +1,7 @@
+// "Change to 'builder.append(1+1).append(s).append("  ")'" "true"
+class Test {
+  String s;
+  void bar(StringBuilder builder) {
+    buil<caret>der += 1 + 1 + s + "  ";
+  }
+}