Setup python bridge between treqs-ng and node

User Story

As a maintainer, I want a dependable bridge between the main extension code and treqs-ng so that I have to fix fewer breaking changes.

Traceability

• Related to: #
• T-Reqs ID:
• Req label: REQ-2.1

Acceptance criteria

• All currently planned features shall be supported
• A JSON-based interface shall be provided from the standard I/O streams
• Unit tests are added where applicable