[Feat] Add support for Sideloading Browser Apps and Games

[flavioislima]

This PR adds the support to add a URL for a sideload App.

Extending even more the capabilities of Heroic since now it can be used for several other purposes from launching Xcloud, Nvidia GeForceNow, or even Video Streaming services like Netflix, HBO Max, or YouTube. I am sure this will be useful to someone to make devices like the Steam Deck even more flexible.

By default, all browser apps will be launched in fullscreen. We can add a setting for it in the future if people need it. For now, let us keep like this.

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Use the following Checklist if you have changed something on the Backend or Frontend:

• Tested the feature and it's working on a current and clean install.
• Tested the main App features and they are still working on a current and clean install. (Login, Install, Play, Uninstall, Move games, etc.)
• Created / Updated Tests (If necessary)
• Created / Updated documentation (If necessary)

[imLinguin]

Looks good overall, that feature seems nice. However I'm missing a way to close the window properly, sure there is a AbortController like for games. I just don't see how one could close the game in gamescope session without killing whole process tree using Quit Game from Deck overlay. (Just a thought, killing the process isn't that bad after all)

Also left small comments for you to consider

[flavioislima]

Looks good overall, that feature seems nice. However I'm missing a way to close the window properly, sure there is a AbortController like for games. I just don't see how one could close the game in gamescope session without killing whole process tree using Quit Game from Deck overlay. (Just a thought, killing the process isn't that bad after all)

Have you tried?
I will test on the Steam deck later but based on how HyperPlay is behaving, it works just fine there.

[imLinguin]

That was just a thought I had. I'll test the feature later

[slynobody]

thank you! maybe just a little early to ask: is each webapp isolated from each other and/or could you give them / alter specific user-data-dirs? (user facing options would also be great to alter eachs specific ://flags/ as well as cookie / cache-deletion policy)

[flavioislima]

thank you! maybe just a little early to ask: is each webapp isolated from each other and/or could you give them / alter specific user-data-dirs? (user facing options would also be great to alter eachs specific ://flags/ as well as cookie / cache-deletion policy)

For now they are isolated from each other. I think it's safer this way.

[imLinguin]

It's worth noting they are isolated based on the domain of provided URL

[flavioislima]

not a related change, just a small fix to my previous PR.