Implement periodic refresh for server list

[devel60-alt]

first time ever touching lua (why is there no +=)
not sure how else to do a nonblocking timer, and this way seemed the simplest anyways

[Vlad118]

It should be checked that this does not cause a lag/stutter, as it does when manually clicking refresh.

[devel60-alt]

oop i completely forgot about this sorry
but it doesn't really affect performance, i've been using this mod quite frequently for splitscreen, and neither player got stutters from refreshing

[Vlad118]

I think this will still stutter, dependent on internet connection (as calling the refresh function by itself causes a freeze for me, for example). This should be moved to Rust-side as the HTTP request response is blocking in Lua.