add mod list update interval control

[notimaginative]

Adds ability for the mod list to be updated hourly, daily, or manually. Also removes extra load of mod list data on launch which hindered app startup speed.

[wookieejedi]

Just noting here that I have been using a Knossos version with @notimaginative's PRs merged in for months, and the quality of life updates these PRs provide has been exceptionally useful. @Goober5000 or others who have merge access, I would vote to merge these PRs in so they can be used by the larger populace using Knossos :)

[Goober5000]

Okey dokey