Implement test execution routes

[nicosammito]

The communication pattern for execution:

• Endpoint to execute given action function async (response only execution_id) (Adapter -> Aquila)
• Endpoint to execute given action function sync (response is result of execution) (Execution -> Aquila)
• Endpoint to ask for result by given execution_id (Execution -> Aquila)

[raphael-goetz]

I would reduce this issue to just the routes needed for test execution.

• sync service to send a test execution and receive its result