GetConfiguration without key

[MateoGreil]

Is your feature request related to a problem? Please describe.
The current implementation of get_configuration with ocpp_key = "" (which corresponds to requesting all configurations in the OCPP protocol) does not properly store the result in the Timestamp Config Response attribute. When key = "", it only saves the first value as key: first_value, instead of returning all the keys and values.

Describe the solution you'd like
When making a get_configuration request with ocpp_key = "", the desired behavior is to have all the keys and values returned and stored properly, not just the first value. This would allow retrieving all the configurations of the charger when an empty key is provided.

Furthermore, it would be beneficial to have an ocpp_configurations sensor that gets updated on each boot and each set_configuration call. This attribute should return the result of get_configuration with key = "", providing a way to view all the configurations of the charger.

Describe alternatives you've considered
Today, without this feature, I use the log to know the configuration of my charger.

Additional context
When the get_configuration is done with a key (it's working properly):

When the get_configuration is done without a key (it's not working properly):