Add Delete-Everything button

The title says it all :D Please add a button/menu entry to the menu, that deletes all the data.

Injecting RccStorage should give you the storage service that is currently used. That service should provide all the means to delete all the data :)

Note: Actions already have a '.confirmationMessage' property that – if not falsy – will trigger a confimation modal before executing the action. That might not be enough in this case; any thoughts on that?

Take a look at lib/features/src/storage to get an impression of how the storage services are implemented. We are currently only using IndexedDbItemStorage.

Where to start?

• lib/common/src/storage-provider
• lib/features/src/storage

Requirements

• There's a button in the menu that deletes all the data
• Double check if the user really wants to delete all the data.
• Add a unit test