Allow port number to be specified with tcp hostname

[djholt]

This is minor but useful when a different port number needs to be specified (when tunneling over SSH, for example).

[codecov]

Codecov Report

Attention: Patch coverage is 80.00000% with 1 line in your changes missing coverage. Please review.

Project coverage is 60.72%. Comparing base (584a14f) to head (5cc9627).
Report is 19 commits behind head on master.

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

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #673      +/-   ##
==========================================
+ Coverage   60.70%   60.72%   +0.02%     
==========================================
  Files          24       24              
  Lines        3667     3672       +5     
==========================================
+ Hits         2226     2230       +4     
- Misses       1441     1442       +1     

Flag	Coverage Δ
unittests	60.72% <80.00%> (+0.02%)	⬆️

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[ianmcorvidae]

Looks like the test failure is unrelated, to do with test fuzzing for some other stuff. This looks good, thanks!