nxos - _get_merge_diff - get_config - allow "full/all" config to be compared to allow better state enforcement

[ITJamie]

Description of Issue/Question

when https://github.com/napalm-automation/napalm/blob/develop/napalm/nxos/nxos.py#L236 is adjusted to
running_config = self.get_config(retrieve="running", full=True)["running"] it allows easier management with salt.
Since with the change, using netconfig.managed with a template it will be able to see default config options eg "no shutdown" and thus will not make any config adjustments

It would be nice to have a configurable option for this

Did you follow the steps from https://github.com/napalm-automation/napalm#faq

(Place an x between the square brackets where applicable)

• Yes
• [] No

Setup

napalm version

(Paste verbatim output from pip freeze | grep napalm between quotes below)

napalm==4.0.0

Network operating system version

(Paste verbatim output from show version - or equivalent - between quotes below)

        show version:
            Cisco Nexus Operating System (NX-OS) Software
            TAC support: http://www.cisco.com/tac
            Copyright (C) 2002-2022, Cisco and/or its affiliates.
            All rights reserved.
            The copyrights to certain works contained in this software are
            owned by other third parties and used and distributed under their own
            licenses, such as open source.  This software is provided "as is," and unless
            otherwise stated, there is no warranty, express or implied, including but not
            limited to warranties of merchantability and fitness for a particular purpose.
            Certain components of this software are licensed under
            the GNU General Public License (GPL) version 2.0 or
            GNU General Public License (GPL) version 3.0  or the GNU
            Lesser General Public License (LGPL) Version 2.1 or
            Lesser General Public License (LGPL) Version 2.0.
            A copy of each such license is available at
            http://www.opensource.org/licenses/gpl-2.0.php and
            http://opensource.org/licenses/gpl-3.0.html and
            http://www.opensource.org/licenses/lgpl-2.1.php and
            http://www.gnu.org/licenses/old-licenses/library.txt.

            Software
              BIOS: version 5.3.1
             NXOS: version 9.3(9)
              BIOS compile time:  05/17/2019
              NXOS image file is: bootflash:///nxos.9.3.9.bin
              NXOS compile time:  2/4/2022 7:00:00 [02/04/2022 08:54:27]


            Hardware
              cisco Nexus 3172 Chassis
              Intel(R) Core(TM) i3-3227U CPU @ 2.50GHz with 8151196 kB of memory.
              Processor Board ID FOC21460VXH

              Device name: 
              bootflash:   14048256 kB
              usb1:               0 kB (expansion flash)

            Kernel uptime is 158 day(s), 8 hour(s), 48 minute(s), 50 second(s)

            Last reset at 46026 usecs after Thu Mar 10 11:54:00 2022
              Reason: Reset due to upgrade
              System version: 7.0(3)I7(9)
              Service:

            plugin
              Core Plugin, Ethernet Plugin

            Active Package(s):

Steps to Reproduce the Issue

Error Traceback

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