JoinLinesHandler: convert end of line comments as a separate stage for all lines at once

GitOrigin-RevId: 25aa0068b8a1bf4b2a2c08ccf8c086bb49aa30ae

java/java-tests/testData/codeInsight/joinLines/ConvertManyEndOfLineComments.java

@@ -0,0 +1,7 @@
+class A {
+  void test() {
+    <selection>int foo; //foo
+    int bar; //bar
+    int baz; //baz</selection>
+  }
+}