add --set-is-unmessageable to CLI commands

[pdxlocations]

allows:
meshtastic --set-is-unmessagable true
meshtastic --set-is-unmessageable true
meshtastic --set-is-unmessagable false
meshtastic --set-is-unmessageable false

[codecov]

Codecov Report

Attention: Patch coverage is 92.30769% with 1 line in your changes missing coverage. Please review.

Project coverage is 59.82%. Comparing base (c55f1ef) to head (17f7e8e).
Report is 29 commits behind head on master.

Files with missing lines	Patch %	Lines
meshtastic/node.py	75.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #794      +/-   ##
==========================================
- Coverage   59.90%   59.82%   -0.09%     
==========================================
  Files          24       24              
  Lines        4163     4184      +21     
==========================================
+ Hits         2494     2503       +9     
- Misses       1669     1681      +12     

Flag	Coverage Δ
unittests	59.82% <92.30%> (-0.09%)	⬇️

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[ianmcorvidae]

I'm thinking this should be rearranged a little to match other code, but otherwise looks reasonable to me.

[ianmcorvidae]

one tiny thing but otherwise good to go. feel free to ping me in discord if I lose track of it again