The logic in Device.get_isa should be somewhere else

All this default annotation logic should be pulled out into a function or a method on ISAs.

def get_isa(self, oneq_type=None, twoq_type=None) -> ISA:
    """
    Construct an ISA suitable for targeting by compilation.
    This will raise an exception if the requested ISA is not supported by the device.
    """
    if oneq_type is not None or twoq_type is not None:
        raise ValueError("oneq_type and twoq_type are both fatally deprecated. If you want to "
                         "make an ISA with custom gate types, you'll have to do it by hand.")

    qubits = [Qubit(id=q.id, type=None, dead=q.dead, gates=[
        MeasureInfo(operator="MEASURE", qubit=q.id, target="_",
                    fidelity=self.specs.fROs()[q.id] or DEFAULT_MEASURE_FIDELITY,
                    duration=DEFAULT_MEASURE_DURATION),
        MeasureInfo(operator="MEASURE", qubit=q.id, target=None,
                    fidelity=self.specs.fROs()[q.id] or DEFAULT_MEASURE_FIDELITY,
                    duration=DEFAULT_MEASURE_DURATION),
        GateInfo(operator="RZ", parameters=["_"], arguments=[q.id],
                 duration=PERFECT_DURATION, fidelity=PERFECT_FIDELITY),
        GateInfo(operator="RX", parameters=[0.0], arguments=[q.id],
                 duration=DEFAULT_RX_DURATION, fidelity=PERFECT_FIDELITY)] + [
            GateInfo(operator="RX", parameters=[param], arguments=[q.id],
                     duration=DEFAULT_RX_DURATION,
                     fidelity=self.specs.f1QRBs()[q.id] or DEFAULT_RX_FIDELITY)
            for param in [np.pi, -np.pi, np.pi / 2, -np.pi / 2]])
        for q in self._isa.qubits]
    edges = [Edge(targets=e.targets, type=None, dead=e.dead, gates=[
                GateInfo(operator="CZ", parameters=[], arguments=["_", "_"],
                         duration=DEFAULT_CZ_DURATION,
                         fidelity=self.specs.fCZs()[tuple(e.targets)] or DEFAULT_CZ_FIDELITY)])
             for e in self._isa.edges]
    return ISA(qubits, edges)

Start at Device.get_isa and inspect the referenced ISA, Qubit, Edge, MeasureInfo, and GateInfo definitions. Move the default annotation construction into an appropriate function or ISA method, preserving the existing validation and generated gates and edges; done means Device.get_isa no longer owns that logic.