Changes to Create a custom avatar

the data/id response's property type changed from no type to string for status 201

added the optional property data/suggested_voice_id to the response with the 201 status

removed subschema #1: Stock avatar ID subschema #2: Custom avatar ID from the data/id response property oneOf list for the response status 201

the data/id response's property pattern ^[A-Za-z0-9][A-Za-z0-9._:-]{0,127}$ was added for the status 201

endpoint added