Draft: Json chooser v2: A complex chooser to handle options

[columbarius]

If we want to query the user for options like persist_mode we need to send more data than just the name of the output. We also need sth. more complex when window selection is possible.

In any case this is a PoC sending the data encoded via json between chooser and xdpw in both directions. The scheme is versioned with version (breaking) and revision (backwards compatible on the xdpw side).

Note: man-page has still the scheme from #105 . The new scheme is demonstrated in chooser-protocol.json.

Windows got an additional arbitrary id, since two toplevels can have the same app_id and title.

Supersedes: #105

CC: @emersion

[columbarius]

Updated this with an idea to separate the chooser by using choser, chooser_opts and a target struct.
There are still open todos like collecting the persist_mode.

[YellowOnion]

being able to choose the fps would be nice as well, max_fps could be a default.