Enhancements to "Convert to string interpolation"

[bjansen]

It seems to me that the current behavior of "Convert to string interpolation" could be improved a little. Given this example code:

value foo = "\"" + name + "\" \"" + version + "\"";

I get inconsistent behavior depending on which + the quick assist is called on:

• on the first +, it results in "\"``name``" + "\" \"" + version + "\""
• ...
• on the last + it results in "\"``name``\" \"``version``\""

In my opinion, it should always result in "\"``name``\" \"``version``\"".

[bjansen]

Also, for some reason, "a" + "b" is transformed to "a``"b"``", instead of simply "ab". I think it should be easy to detect string literals and avoid surrounding them with backticks.