Netscaler multiple partition support

[smallsam]

Pre-Request Checklist

• Passes rubocop code analysis (try rubocop --auto-correct)
• Tests added or adapted (try rake test)
• Changes are reflected in the documentation
• User-visible changes appended to CHANGELOG.md

Description

Citrix Netscalers have functionality for logical partitioning, where each partition has its own config. This pull request enhances oxidized to check for presence of these additional config partitions and retrieves the configuration from them if present.

It is modeled on the asa model which has similar logical config separation in contexts.

[codecov-io]

Codecov Report

Merging #1596 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1596   +/-   ##
=======================================
  Coverage   62.62%   62.62%           
=======================================
  Files          30       30           
  Lines        1493     1493           
=======================================
  Hits          935      935           
  Misses        558      558

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[mortzu]

Can you fix the conflict

[smallsam]

I've rebased and updated the changelog in line with the new format. I've no longer got access to a netscaler to test this change on, but the rebase should only have impacted the changelog.

[mortzu]

Can you fix the conflict again (sorry. We have to change the CHANGELOG to a more flexible variant...)