Fixing missing hyperparameters of GlobalPhase

[JerryChen97]

Context:
qml.GlobalPhase does not set its hyperparameters during initialization. This caused certain bugs, e.g.

>>> np.allclose(qml.GlobalPhase(0.123).matrix(), qml.GlobalPhase(0.123).sparse_matrix().toarray())
False
>>> qml.GlobalPhase(0.123).matrix().shape
(1, 1)
>>> qml.GlobalPhase(0.123).sparse_matrix().shape
(2, 2)
>>> qml.GlobalPhase(0.123).matrix()
array([[0.99244503-0.12269009j]])
>>> qml.GlobalPhase(0.123).sparse_matrix().toarray()
array([[0.99244503-0.12269009j, 0.        +0.j        ],
       [0.        +0.j        , 0.99244503-0.12269009j]])

where GlobalPhase.sparse_matrix() did the calculation wrongly because it never received correct n_wires from hyperparameters, which is required by the base class Operator

Description of the Change:

Benefits:

Possible Drawbacks:

Related GitHub Issues:

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