Update trailing comma match logic, add tests

Updates the traling comma code to attempt to handle multiline non-block bodies when
adding traling commas to blocks. Also add and update tests to cover better
the interactions between trailing commas and wrapping match arms.

tests/source/match-block-trailing-comma.rs

@@ -8,6 +8,7 @@ fn foo() {
             "line1";
             "line2"
         }
-        b => "bar",
+        b => (aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa,
+              bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb),
     }
 }