Simplify the regular expression for FluentRe.match('a').optional().possessive()

Let's say I have the following code:

```
FluentRe.
   match('a').
   optional().
   possessive();
```
Currently, it makes this regular expression: `(?:\Q$\E)?+`.  Please simplify to `\$?+`.

This will make it easier for humans to read the regular expression.