Extend add_object for new server-side feature breakOnDuplicate

Extend the add_object() method for the duplicate-detection feature supported by the server. MISP was extended to allow detection of duplicate object-attribute collections - see https://github.com/MISP/MISP/issues/2826 - but today there appears to be no way to invoke that feature from PyMISP.

I'll be glad to propose a change to api.py, but it's not obvious how to pass the parameter that's read here:

https://github.com/MISP/MISP/blob/ca5043a184b8eec53fb4093377fc4a727d4345cf/app/Controller/ObjectsController.php#L224

Here's client code you might use to test the feature:

#!/usr/bin/env python3

import sys
import urllib3
from pymisp import PyMISP, MISPAttribute, MISPEvent, MISPObject
urllib3.disable_warnings(urllib3.exceptions.InsecureRequestWarning)

def add_phishing_obj(misp_client, event):
    """Create an object on an event with a single attribute"""
    obj = MISPObject(name='phishing', strict=True)
    obj.add_attribute(object_relation='url', simple_value='https://simple.tld/')
    response = misp_client.add_object(event.id, obj, pythonify=True)  # *NEED NEW PARAMETER HERE*
    print('added obj on evt: {}'.format(obj.to_json(sort_keys=True, indent=4)))
    return obj

misp_client = PyMISP(url='https://misp:48752', key='keykeykey', ssl=False)
if not misp_client:
    print('PyMISP() failed\n', file=sys.stderr)
    sys.exit(1)

event = MISPEvent()
event.distribution = 0  # internal
event.published = False
event.info = 'Test event for dupes'
event = misp_client.add_event(event, pythonify=True)
print('created event:\n{}'.format(event.to_json(sort_keys=True, indent=4)))

obj1 = add_phishing_obj(misp_client, event)
obj2 = add_phishing_obj(misp_client, event)

Start in api.py at PyMISP.add_object() and compare its request parameters with the server-side ObjectsController.php reference linked in the issue. Use the provided duplicate-object example to verify that the new option reaches the server and that duplicate detection behaves as expected.