[UI] Sideloaded games cover art improvements

[WillyJL]

Problem description

Games from epic store have dedicated tall (art_square) and wide (art_cover) images, the library grid uses the tall image usually except the first game in the recently played section which is 2 spots wide and uses the wide (art_cover) image (as per #2750).

Sideloaded games (Add Game without using a store) only select a tall image and use it for the wide image aswell, leading to a cropped image that looks worse than having the most recently played game be 1 spot wide.

Feature description

1. Use a separate wide cover image for sideloaded games. For example, "Add Game" could run 2 search queries on SteamGridDB, one for a tall image and one for a wide image, and show both to the user.
2. Having a way to edit the game images after adding a sideloaded game would be useful (tying into 1: would allow users to change the wide image for existing games after this feature is added, without editing json files manually).
3. Since the sideloaded game image search uses SteamGridDB, would be neat to be able to click on the result image to view all results from the query and choose another one (first result is not always the best); of course can do it manually in browser, but having it in the launcher would be nice.

Alternatives

No response

Additional information

As a workaround for 1, one can edit the ~/.config/heroic/sideload_apps/library.json file to change the art_cover image to a wide one.

[WillyJL]

After looking into it, I see this does not use SteamGridDB directly but rather the steamgrid-proxy instance at https://steamgrid.usebottles.com, which only returns the first result.

This means:

• 3 is not possible (unless we implement and switch to a dedicated steamgrid proxy for Heroic that returns multiple results)
• 1 is currently not possible: while the proxy supports different image types, including ones that would work for a wide cover art, the https://steamgrid.usebottles.com instance is using an outdated version of the proxy without this functionality

I suppose for now I'll draft a PR for implementing 1 with the Bottles instance in hopes of it being updated, if the Bottles team decides it is not their concern (which would be totally fair) then will need to think about deploying a dedicated proxy for Heroic and maybe reconsider 3.

[RondoRevolution]

I know this is currently stuck, but I wanted to point out that there's also the issue of the .desktop file icon used, where currently, the generated file uses the main cover art, resulting in often ugly and tall images when searching for the sideloaded app/game in the system's app launcher menu.