Move DIDComm out of core to separate @credo-ts/didcomm module

[TimoGlastra]

Also extract all the config specifc to DIDComm from the default config. It's a bit weird now that DIDComm endpoint is configured trhough global endpoints config, but for OpenID you have to configure it on the module.

May also be nice to have some default options. So that you can just start the agent and /didcomm is used for didcomm, /oid4vci is used for openid issuance, etc..

[TimoGlastra]

Shoudl probably also make registerInboundTransport and registerOutboundTransport config options in the DIDComm module