refactor(api): restructure bolt package (#1981)

* refactor(api): bolt package refactor

* refactor(api): refactor bolt package

api/bolt/migrator/migrate_dbversion0.go

@@ -0,0 +1,36 @@
+package migrator
+
+import (
+	"github.com/boltdb/bolt"
+	"github.com/portainer/portainer"
+	"github.com/portainer/portainer/bolt/user"
+)
+
+func (m *Migrator) updateAdminUserToDBVersion1() error {
+	u, err := m.userService.UserByUsername("admin")
+	if err == nil {
+		admin := &portainer.User{
+			Username: "admin",
+			Password: u.Password,
+			Role:     portainer.AdministratorRole,
+		}
+		err = m.userService.CreateUser(admin)
+		if err != nil {
+			return err
+		}
+		err = m.removeLegacyAdminUser()
+		if err != nil {
+			return err
+		}
+	} else if err != nil && err != portainer.ErrObjectNotFound {
+		return err
+	}
+	return nil
+}
+
+func (m *Migrator) removeLegacyAdminUser() error {
+	return m.db.Update(func(tx *bolt.Tx) error {
+		bucket := tx.Bucket([]byte(user.BucketName))
+		return bucket.Delete([]byte("admin"))
+	})
+}