Fix #12579 create cable and add another error

[netopsab]

Fixes: #12579

Add get_extra_addanother_params function to CableEditView which return :

• previous selected parent object (a_termination_device or a_termination_powerpanel or a_termination_circuit)
• previous selected termination type (a_termination_type and b_termination_type)

[jeremystretch]

We can't assume the A side will be a device; it could also be a power feed or circuit termination.

[netopsab]

Thank you for the review. I have updated this PR as requested.

[DanSheps]

You could instead do:

Suggested change

	pk = resolve(request.GET.get('return_url')).kwargs.get('pk')
	a_type = CABLE_TERMINATION_TYPES.get(request.GET.get('a_terminations_type'))
	if hasattr(a_type, 'device'):
	params.update({'termination_a_device': pk})
	elif hasattr(a_type, 'power_panel'):
	params.update({'termination_a_powerpanel': pk})
	elif hasattr(a_type, 'circuit'):
	params.update({'termination_a_circuit': pk})
	for key in request.POST:
	if 'device' in key or 'power_panel' in key or 'circuit' in key:
	params.update({key: request.POST.get(key})

This lets you remove the resolve import and also improves the workflow for people adding multiple cables between two separate devices.

[netopsab]

Thank you for the suggestion. I have updated this PR as requested.

[jeremystretch]

Thanks @netopsab!