rethink how mod loader options are set per-project

[Qubus0]

it's a bit annoying to upgrade the mod loader currently, since you have to pay attention which files you overwrite when replacing the full mod loader folder. specifically, it's very easy to accidentally replace the options.tres and everything in the profiles folder, which resets all the settings back to default.

copying these profiles to a new location helps, but still leaves the options.tres open for mistakes, since the ModLoaderStore expects it at a specific path, without a way to change that path (without changing the ml source code, which we want to avoid)

additionally, options_profile.gd has some fields like steam_id and semantic_version, which have a getter that is meant to be overridden if the game already has a centralized place to get that info from. adding custom setters there, again, defeats the purpose of not changing the mod loader source since those changes can easily be reverted during an upgrade.

optimally we want all settings to be in a different folder outside the mod loader, both for the resources and the custom getters