core: Create options to switch on/off toasts for scans

Closes daiquiri-tomo#358 (closed)

This PR introduce a side floating panel to deal with global options.

Implement a switch to enable/disable the use of toasts when scans even are received.

This location could be used for more configuration in the future.

This uses the metadata cache. We will have to be careful of cache.cache.toasts?.scans?.[1], because this could change in the future.