NX-OS: add missing reference tracking for snmp-server user use-ipv[46]acl

[dhalperi]

Fix #9183 and batfish/pybatfish#922

[batfish-bot]

This change is 

[codecov]

Codecov Report

Attention: Patch coverage is 71.42857% with 4 lines in your changes missing coverage. Please review.

Project coverage is 72.71%. Comparing base (cfd090b) to head (f2055fc).
Report is 44 commits behind head on master.

Files with missing lines	Patch %	Lines
...mar/cisco_nxos/CiscoNxosControlPlaneExtractor.java	66.66%	2 Missing and 2 partials ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #9184   +/-   ##
=======================================
  Coverage   72.71%   72.71%           
=======================================
  Files        3313     3313           
  Lines      169928   169942   +14     
  Branches    20016    20018    +2     
=======================================
+ Hits       123560   123577   +17     
+ Misses      37205    37200    -5     
- Partials     9163     9165    +2     

Files with missing lines	Coverage Δ
...esentation/cisco_nxos/CiscoNxosStructureUsage.java	100.00% <100.00%> (ø)
...mar/cisco_nxos/CiscoNxosControlPlaneExtractor.java	78.81% <66.66%> (-0.04%)	⬇️

... and 2 files with indirect coverage changes

[progwriter]

Reviewed 5 of 5 files at r1, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @arifogel and @SLarkworthy)