[BUG] `aegis_director`: pymoveit2 synchronous service call ends in a deadlock

### Description

# The problem

Any synchronous calls to ROS 2 services (using `pymoveit2`) results in a nasty wait deadlock. To my best knowledge there is problem with a proper executor spinning (due to handling it with `threading` package).

Probably it is the same issue as with the gripper: #39

# Temporary workaround
Call everything asynchronously and introduce a naive sleep/wait in the code.

# Idea for solution
Rewrite the `aegis_director` in C++ as a gRPC server.

### References

* https://github.com/AGH-CEAI/aegis_gym/issues/27