Handle user delete (#1113)

Implement user deletion across all IDP-ss. Expires all user peers
when the user is deleted. Users are permanently removed from a local
store, but in IDP, we remove Netbird attributes for the user
untilUserDeleteFromIDPEnabled setting is not enabled.

To test, an admin user should remove any additional users.

Until the UI incorporates this feature, use a curl DELETE request
targeting the /users/<USER_ID> management endpoint. Note that this
request only removes user attributes and doesn't trigger a delete
from the IDP.

To enable user removal from the IdP, set UserDeleteFromIDPEnabled
to true in account settings. Until we have a UI for this, make this
change directly in the store file.

Store the deleted email addresses in encrypted in activity store.

management/server/activity/codes.go

@@ -104,6 +104,8 @@ const (
 	UserBlocked
 	// UserUnblocked indicates that a user unblocked another user
 	UserUnblocked
+	// UserDeleted indicates that a user deleted another user
+	UserDeleted
 	// GroupDeleted indicates that a user deleted group
 	GroupDeleted
 	// UserLoggedInPeer indicates that user logged in their peer with an interactive SSO login
@@ -162,6 +164,7 @@ var activityMap = map[Activity]Code{
 	ServiceUserDeleted:                        {"Service user deleted", "service.user.delete"},
 	UserBlocked:                               {"User blocked", "user.block"},
 	UserUnblocked:                             {"User unblocked", "user.unblock"},
+	UserDeleted:                               {"User deleted", "user.delete"},
 	GroupDeleted:                              {"Group deleted", "group.delete"},
 	UserLoggedInPeer:                          {"User logged in peer", "user.peer.login"},
 	PeerLoginExpired:                          {"Peer login expired", "peer.login.expire"},