JoinLinesHandler: separate processing of raw handlers; disable formatting for PSI handlers

GitOrigin-RevId: 59f8fe15c8ca883f02f968ac08a5aa490d4686b2

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

@@ -0,0 +1,17 @@
+class A {
+  void test() {
+    <selection>/* hello
+    one
+    two
+    three
+    */
+    int foo;
+    foo = 5;
+    int bar = 0;
+    bar = 6;
+    int baz; /* goodbye
+    one
+    two
+    three */</selection>
+  }
+}