Setup notification verbosity per resource

[VincentBougie]

As we speak, the global variable named GHC_NOTIFICATIONS_VERBOSITY is the one in charge to determine when an email should be send consistently or on an status change.

This global variable should be eliminated and added inside the database architecture in order to be able to set that variable for each and single resource, and then, send emails according to that variable.

[justb4]

We could keep global GHC_NOTIFICATIONS_VERBOSITY as a default, which can be overruled per-Resource. Also will work well with upgrades from older GHC versions. Bit similar to how email notification works (global GHC_NOTIFICATIONS_EMAIL can optionally be extended per-Resource.

Though remember that with individual Resource scheduling like every 5 minutes, verbose becomes very verbose!