New method update_until_and_get_variables

[BSchilperoort]

Communication with grpc4bmi is quite slow. Often much slower than updating a locally running model. In many workflows this makes users not want to use containerized models (especially for 1D models).

We could speed up their workflows with a new grpc4bmi method update_until_and_get_variables, which:

• Takes a time to update until, and the names of variables the user wants to store
• The grpc server will update the model, and store the variables
• Once the target time is reached, the grpc server will transfer the collected data to the user

As there is a loop running inside the container, this will greatly improve performance.

[BSchilperoort]

Another way to improve performance could also be to use a rust grpc server (with Python bindings e.g. pyo3).

"tonic", a rust gRPC server+client is 20x faster than python's grpc (which is one of the slowest gRPC implementations).