Alternative to Symfony Httplug Async

[Nyholm]

This is a alternative to #159

Im not sure which one I like better.

This will check if a PSR17Factory can be found before accepting Symfony's HttplugClient as a candidate.

[onEXHovia]

@Nyholm thanks, it's works for me

[XWB]

This change works for me as well.

But the tests still fail.

[Nyholm]

PR is updated

[Nyholm]

Wohoo, the "install tests" are useful. I found a bug =)

We still check for interfaces. Ie, Symfony client does not work without the Http\Message\RequestFactory (interface)

[dbu]

looks good to me, thanks!

feel free to merge and tag a new release if there is nothing else we should merge first.

[Nyholm]

Thank you