Instruction comparison fails when parameters are arrays

[gadial]

Information

• Qiskit Terra version: 0.8.2
• Python version: 3.6
• Operating system: Linux

What is the current behavior?

Comparing two instructions that have matrix parameters fails ungracefully with
ValueError: The truth value of an array with more than one element is ambiguous. Use a.any() or a.all()

Matrix parameters for instructions are currently generated when converting Aer's errors to instructions.

Steps to reproduce the problem

The following code raises this error:

from qiskit import QuantumRegister, QuantumCircuit
from qiskit.providers.aer.noise.errors.standard_errors import pauli_error
qr = QuantumRegister(1, 'qr')
circuit = QuantumCircuit(qr)
error = pauli_error([('X', 0.25), ('I', 0.75)])
circuit.append(error.to_instruction(), [qr[0]])
circuit == circuit

What is the expected behavior?

Correct element-by-element comparison of the matrices, using numpy.isclose for almost-identical matrices.

Suggested solutions

Line 99 in instruction.py needs to be modified; it seems type-checking the parameter is needed (maybe isinstance(self_param, numpy.ndarray?). For Numpy arrays numpy.equalandnumpy.iscloseworks and returns a boolean array of results, on whichall()` can be used.

[gadial]

This is currently blocking a PR in Aer: Qiskit/qiskit-aer#239