Complete event system

[binarybaron]

This issue is for tracking all features related to sending all required events from host to guest.

• [x] #93
• [x] #43
• [x] #103

[Einliterflasche]

On the host side we hard code the event names (e.g. const TIMELOCK_CHANGE_EVENT_NAME: &str = "timelock-change;") which we then manually use on the guest side (listen<...>("timelock-change")). ideally we could also #[typeshare] these constants

[binarybaron]

We can put all our events into one big enum and send that over the event system over one event channel/name. This'll give us some type safety (won't have to cast received objects via listen<TYPE>) and will result in less event names having to be hardcoded on both host and guest side.