Change "port status" to "port settings" and make "port set" more explicit

[davidk]

This set of commits changes ntgrrc CLI arguments to fall more in-line with how poe status and poe settings are currently being used and structured. port set code was also changed to indicate that it belongs in its own separate space.

Other minor updates:

• README.md updated (following the changed CLI convention)
• When printing JSON, there should be an indication of where the output comes from (poe settings vs port settings)

[codecov-commenter]

Codecov Report

Merging #41 (135dcc7) into main (beabeb5) will not change coverage. The diff coverage is 15.00%.

@@           Coverage Diff           @@
##             main      #41   +/-   ##
=======================================
  Coverage   41.25%   41.25%           
=======================================
  Files          16       16           
  Lines         863      863           
=======================================
  Hits          356      356           
  Misses        497      497           
  Partials       10       10           

Impacted Files	Coverage Δ
port_settings.go	32.14% <0.00%> (ø)
port_set.go	34.84% <33.33%> (ø)
poe_settings.go	70.88% <100.00%> (ø)
poe_status.go	74.15% <100.00%> (ø)

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