Make OpIdentifier serializable for all inputs

[epelaaez]

Closes #6292

Makes OpIdentifier serializable for inputs that are instances of classes. For example,

qubits = cirq.LineQubit.range(1)
cliff = cirq.SingleQubitCliffordGate.from_xz_map((cirq.X, False), (cirq.Z, False))
op_id = cirq.OpIdentifier(cliff, qubits[0])
print(repr(op_id), "\n")
print(cirq.to_json(op_id))

will output

cirq.devices.noise_utils.OpIdentifier(cirq.CliffordGate.from_clifford_tableau(cirq.CliffordTableau(1,rs=np.array([False, False], dtype=np.dtype('bool')), xs=np.array([[True], [False]], dtype=np.dtype('bool')),zs=np.array([[False], [True]], dtype=np.dtype('bool')), initial_state=0)), cirq.LineQubit(0)) 

{
  "cirq_type": "OpIdentifier",
  "gate_type": {
    "cirq_type": "SingleQubitCliffordGate",
    "n": 1,
    "rs": [
      false,
      false
    ],
    "xs": [
      [
        true
      ],
      [
        false
      ]
    ],
    "zs": [
      [
        false
      ],
      [
        true
      ]
    ]
  },
  "qubits": [
    {
      "cirq_type": "LineQubit",
      "x": 0
    }
  ]
}

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[vtomole]

@epelaaez Please sign the CLA

[codecov]

Codecov Report

All modified lines are covered by tests ✅

Comparison is base (c696323) 97.89% compared to head (6e4876f) 97.89%.
Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #6295   +/-   ##
=======================================
  Coverage   97.89%   97.89%           
=======================================
  Files        1104     1104           
  Lines       95874    95887   +13     
=======================================
+ Hits        93852    93866   +14     
+ Misses       2022     2021    -1     

Files	Coverage Δ
cirq-core/cirq/_compat.py	98.71% <100.00%> (+<0.01%)	⬆️
cirq-core/cirq/devices/noise_utils.py	98.66% <100.00%> (+0.03%)	⬆️
cirq-core/cirq/devices/noise_utils_test.py	100.00% <100.00%> (ø)
cirq-ft/cirq_ft/algos/and_gate.py	100.00% <100.00%> (ø)
cirq-ft/cirq_ft/algos/and_gate_test.py	100.00% <100.00%> (ø)
cirq-ft/cirq_ft/algos/hubbard_model.py	98.21% <ø> (ø)
.../cirq_ft/algos/multi_control_multi_target_pauli.py	100.00% <100.00%> (ø)
...-ft/cirq_ft/algos/prepare_uniform_superposition.py	100.00% <ø> (ø)
cirq-ft/cirq_ft/algos/qrom.py	100.00% <ø> (ø)
cirq-ft/cirq_ft/algos/unary_iteration_gate.py	96.26% <ø> (ø)
... and 2 more

... and 1 file with indirect coverage changes

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[vtomole]

LGTM