feat: improve proof api

Description

Added a get single roof request by id and decline a proof request.

Changed: create proof now returns a url if connection is not passed. Accept proof can accept url for oob proof and json for the proof with connection.

NOTE: BREAKING CHANGE IN accept proof request api, now we are using body instead of a url param.

Testing

Tested locally with docker-compose

Checklist

• I have updated the documentation (if necessary)
• I have added unit tests for new functionality (if applicable)
• My code follows the style guidelines of this project
• I have tested this code on my local machine before submitting this MR

Reviewers

@zdravko.iliev

Closes: #35 (closed), #34 (closed)