[2.x] feat: remove `behat/mink` requirement and add new selector API

[kbond]

Fixes https://github.com/zenstruck/browser/pull/15, Fixes https://github.com/zenstruck/browser/issues/12. Fixes https://github.com/zenstruck/browser/issues/37. Fixes #77.

Replacing mink with my own dom system allowed me to create a new selector api (#77). The plan is to extract the dom stuff into a new zenstruck/dom package so it can be utilized by this package + others that need to make dom assertions.

/cc @weaverryan, @jwage, @nikophil, @OskarStark, when/if time permits, I'd appreciate if you could test this in any html-heavy apps you have that use browser. I found and fixed (and added tests) for several edge cases when testing this in my app.

TODO:

• [x] extract zenstruck/dom

[nikophil]

I just saw this issue... sorry for the late reply 😅

It's been a while I have not worked on an "html" app (only json apis, or full messenger apps). Sorry I can't help

[OskarStark]

@kbond I currently don't have time, but you have access to one or two of my projects, so feel free to run them against this branch

[kbond]

Thanks Oskar, I'll try it out on your projects when I pick this PR up again.