Remove the sit param menu option when a region is inactive

[enamkhan]

What It Does
Currently the "Show SIT Parameters" menu option can be selected on inactive regions which will cause an error. I've changed this so that this option is greyed out when the region is inactive. I've also added a check in the command so that the error does not surface when executed from the command palette.

How to Test
Connected to a plex with both active and inactive regions and verified that the menu item for 'Show SIT Parameters' is grayed out when the region is inactive. This will also be the case if multi-select is used and includes an inactive region.

Review Checklist
I certify that I have:

• tested my changes
• added/updated automated tests
• updated the changelog
• followed the contribution guidelines

Additional Comments
Resolves #167

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 93.76%. Comparing base (3786293) to head (5c105f8).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #183   +/-   ##
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  Coverage   93.76%   93.76%           
=======================================
  Files          75       75           
  Lines         770      770           
  Branches       42       43    +1     
=======================================
  Hits          722      722           
  Misses         48       48           

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[enamkhan]

Was using enablement to grey out the SIT Param menu option, however this had a side-effect of not showing the option in the command palette. So have changed to just not showing the menu option when the region is inactive.