fix: map metadata to objectmeta

[vertex451]

Resolves #102

Changes

In case of empty objects with no fields, assign a StringScalar type to it. Works on retrieve and create requests.

Testing

1. Didn't manage to create a Marketplace entry to test the nested metadata because of some limitation, that is why I tested by temporary forcing metav1.ObjectMeta to be a stringScalar - created a configMap using JSON-string.
   After testing return metav1.ObjectMeta to be metav1.ObjectMeta.

2. Retrieved a ConfigMaps, and took its metadata and checked if this string can be converted to JSON.

On-behalf-of: @SAP [email protected]