fix(secure-storage): modify the driver check

The prior check that was there had a chick/egg problem with checking the
driver used for the database before the database was created.

Author: kensodemann

lib/src/index.ts

@@ -159,10 +159,10 @@ export class Storage {
   }
 
   setEncryptionKey(key: string) {
-    if (this.driver !== 'ionicSecureStorage') {
+    if (!this._secureStorageDriver) {
       throw new Error('@ionic-enterprise/secure-storage not installed. Encryption support not available');
     } else {
       (this._secureStorageDriver as any)?.setEncryptionKey(key);
     }
   }
-}
+}