Small Bug in `HHLResult`

[Cmurilochem]

Hi @koenleijnse,

While investigating the preconditioning problem for HHL, I spotted two minor things that wanted to check with you.

hhl-prototype/hhl_prototype/solver/hhl.py

Line 362 in f911099

solution = HHLResult

hhl-prototype/hhl_prototype/solver/hhl_result.py

Lines 57 to 59 in f911099

	def solution(self) -> np.ndarray:
	"""return either the circuit that prepares the solution or the solution as a vector"""
	return self._state

I think that solution above is meant to be an instance of the class so solution = HHLResult() and the return self._solution ?
I do not think these things are changing the final results but you never know the future. Please, let me know what do you think.