feat: migrate one-time and signup tokens to an actor (#1611)

Co-authored-by: Elias Schneider <login@eliasschneider.com>

backend/internal/usersignup/cleanup.go

@@ -1,19 +0,0 @@
-package usersignup
-
-import (
-	"context"
-	"time"
-
-	"gorm.io/gorm"
-
-	datatype "github.com/pocket-id/pocket-id/backend/internal/model/types"
-)
-
-// CleanupExpiredSignupTokens deletes signup tokens that have expired
-// It returns the number of rows removed
-func CleanupExpiredSignupTokens(ctx context.Context, db *gorm.DB) (int64, error) {
-	st := db.
-		WithContext(ctx).
-		Delete(&SignupToken{}, "expires_at < ?", datatype.DateTime(time.Now()))
-	return st.RowsAffected, st.Error
-}