Move all interfaces from List[float] to np.array(float)

[mathfac]

Motivation

While to support more general API and be json friendly we designed agent position and state as List[float] np.array(float) is more efficient in terms of communication between HSIM (Habitat Simulator) as well as is more native for PyTorch usage.

Steps for implementation:

1. Find List[float] in core interfaces and check if it's convenient to switch to np.array(float) and do the switch. Switch in core implementation classes as well.
2. Update Dataset reading and writing code to do conversion between List[float] and np.array(float), as in np.array isn't json serializable.
3. Run mypy to check API are consistent and pytest.