Collections: change "Prefer Exact" mod version selection logic

[LukeNexusMods]

Investigate the logic for the different collection file options and make sure we are doing the right thing for each one.

Currently we are downloading the exact version indicated in the collection manifest, even if that version was archived.
Vortex picks the most recent version in case the file was archived instead.

Some questions:
We could still be grabbing an archived mod depending on when we do the check.
When do we perform the check for which mod version to download?

• Only once at collection fetch then never again?
• At the moment of download of the mod?
• Re-check every time and mark as outdated even if already downloaded?

If we want to check after the initial collection fetch, we need to store that information somewhere.

[Pickysaurus]

https://modding.wiki/en/nexusmods/collections/create/mod-options#install-options

[LukeNexusMods]

Document what Vortex does.

Handle with messaging

[erri120]

There are 3 different update policies:

1. Exact Version Only: use the exact version as described in the data
2. Prefer Exact: use the exact version if it's still available. If the file has been archived or deleted, the newest version of the file should be used.
3. Latest Version: use the latest version

The Vortex default is Prefer Exact when creating collections. The app currently ignores the policy and will always use the exact version only.

[LukeNexusMods]

Does our current collection implementation take the update policies into account?

[LukeNexusMods]

Is this now complete?

[erri120]

Is this now complete?

The investigation is done (#2329 (comment)) but there was no follow-up on what we should do next. We just left it at that since it works in most cases just fine.