Use URL browser protocol to create desktop shortucts

[JosefNemec]

Desktop shortcuts created from Playnite currently start game by starting Playnite executable directly, which has a side effect described in #354. Using browser protocol to start the game (support for something like playnite://start/12321) would probably fix this (but it needs to be tested).

More investigation is needed if it's really worth the effort. Also I'm not sure if registering playnite:// requires elevated rights, which would be a problem.

[JosefNemec]

Update, it should be doable without elevated rights.

[bburky]

If this gets implemented, you could add install and uninstall actions too: playnite://install/12321/ playnite://uninstall/12321. And maybe a way to trigger each of the game's other play actions playnite://start/12321?playaction=1 or whatever.

Currently my non-Steam shortcuts plugin is too much of a hack to do this, but someone asked if it could run installers too: bburky/playnite-non-steam-shortcuts#1. A URL scheme for installation would help I think.

[JosefNemec]

Should be done after #1133 is finished.

[JosefNemec]

Done in devel7 branch (future Playnite 7).