Don't allow --dest with --setlat/lon/alt.

[ianmcorvidae]

(more PRs coming for ensuring other things that don't support --dest don't allow it)

Fixes #545

[codecov]

Codecov Report

Attention: Patch coverage is 33.33333% with 2 lines in your changes are missing coverage. Please review.

Project coverage is 62.38%. Comparing base (70c5a30) to head (cd1ecab).
Report is 1 commits behind head on master.

Files	Patch %	Lines
meshtastic/__main__.py	33.33%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #551      +/-   ##
==========================================
- Coverage   62.41%   62.38%   -0.04%     
==========================================
  Files          14       14              
  Lines        2879     2882       +3     
==========================================
+ Hits         1797     1798       +1     
- Misses       1082     1084       +2     

Flag	Coverage Δ
unittests	62.38% <33.33%> (-0.04%)	⬇️

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