Mod Discovery UI

[Killklli]

This PR adds a Mod Marketplace to the frontend so users can browse and install mods directly in the app. It also includes the install logic, where dependencies are resolved recursively before installing a mod, with basic version checks and error handling.
As a note, each game does need to pass a URL to define the loading, and while I haven't handled it in its own pr.
game.hpp needs std::string marketplace_url; added to it.

It uses libcurl for downloading marketplace data and mod files, and adds the necessary CMake changes to link it.

Backend is fully JSON managed, if a recomp game does not supply the URL themselves it will just hide the button.
It uses the normal installation logic for mods, it just properly wraps the system.

[Killklli]

Update, tested for the new Banjo Kazooie frontend to help clear up some diffs between this and goemon. Also added a search bar and a sort.

[Killklli]

You can use https://raw.githubusercontent.com/Killklli/DemoRecompDiscovery/refs/heads/mod_data/mods.json as your .discovery_url attribute to test for BK.