The button created in #189 should be used to delete a sponsorship level. Upon the actual deletion, the user must be asked for confirmation.
After the deletion, if the API doesn't fire any error, a toast should be showed, saying that the level has been deleted.
Also, if the call gives an error, the user should be notified with a red toast. Note that a level can't be deleted if it contains sponsors.
The button created in #189 should be used to delete a sponsorship level. Upon the actual deletion, the user must be asked for confirmation. After the deletion, if the API doesn't fire any error, a toast should be showed, saying that the level has been deleted. Also, if the call gives an error, the user should be notified with a red toast. Note that a level can't be deleted if it contains sponsors.
Depends on #189 and #184.