stlink: added 1.0.0 release

This is to add a new formula `stlink`, previously attempted at #14175 by @henryeherman two years back. Build system has then changed to autoconf/automake, and now it comes with a (relatively) stable tag back in February.

First attempt in making a brew - please advise if anything's wrong here. Thanks.
OK thanks. Probably we should go with that then. Don't really have much choice there.