Set publicKey dynamically based on IDS certificate from connected keystore

[SebastianOpriel]

Currently DSC implements the ids:publicKey field as a static string in config.json. It would be great to load the IDS (public)key from keystore and set the field according to the actual used value.

IDS-Messaging-Services/core/src/main/java/ids/messaging/core/config/ConfigProducer.java

Line 155 in 7511aab

return SERIALIZER.deserialize(config, ConfigurationModel.class);

Further info:
International-Data-Spaces-Association/DataspaceConnector#34