mutt: awesomize the formula

This PR makes the mutt formula awesome.  See [#20517] and [#20516] and
the discussions in the latter.  To wit:

1. Add suport for HEAD.
2. Make it build a very plain mutt by default (see [#20517]).
3. Bring in most of mutt's configure flags as options and make 
dependencies conditional where needed.
4. Add option `--with-brewed-ssl`.
5. Save the brewer from two different failures.
6. Add the "confirm" patches requested in [#20516].

I didn't squash yet, so that the diffs would be readable.

Thanks to @telemachus for help and suggestions.