Update IoShellyPro3Em.java: included remedy for communication error msg

[sjjh]

Good error messages should contain information how to solve the issue, cf. https://www.nngroup.com/articles/error-message-guidelines/

[codecov[bot]]

Codecov Report

:white_check_mark: All modified and coverable lines are covered by tests.

Additional details and impacted files

@@              Coverage Diff              @@
##             develop    #3203      +/-   ##
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+ Coverage      58.87%   58.87%   +0.01%     
  Complexity       173      173              
=============================================
  Files           2619     2619              
  Lines         113027   113027              
  Branches        8318     8318              
=============================================
+ Hits           66536    66539       +3     
+ Misses         44000    43994       -6     
- Partials        2491     2494       +3     

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[Sn0w3y]

As stated in https://github.com/OpenEMS/openems/issues/3205#issuecomment-2993788158 i would not just Inform the User in the Generic "Communication Failed" Channel as this is too Generic. It coul basically be EVERYTHING why it fails - so it woul be better to create a new Channel for this if we get a Status Code 401 from the Shelly Device. See the /shelly Endpoint

[sjjh]

obsolete due to #3248