Test setup

[khassel]

This is a first step to use electron only when needed in the tests, see #2408.
The idea comes from @fewieden see this comment.

All tests using node-fetch and the translations test can run in server-only-mode instead using electron. So I make them work for this and moved all the remaining electron tests to a new category electron (from e2e) hoping we can shift more electron tests to e2e in the future.

I also changed logger.js again to be silent in the tests.

Tested all changes running mm in server-only mode and running with electron on a pi3.

Some dependencies were updated too.

[codecov-commenter]

Codecov Report

Merging #2664 (c3c5307) into develop (60e0377) will decrease coverage by 1.06%.
The diff coverage is 50.00%.

@@             Coverage Diff             @@
##           develop    #2664      +/-   ##
===========================================
- Coverage    71.01%   69.94%   -1.07%     
===========================================
  Files           17       17              
  Lines          890      895       +5     
===========================================
- Hits           632      626       -6     
- Misses         258      269      +11     

Impacted Files	Coverage Δ
js/logger.js	50.00% <30.00%> (-35.72%)	⬇️
js/app.js	69.74% <100.00%> (-0.60%)	⬇️
js/server.js	85.10% <100.00%> (-6.01%)	⬇️
js/defaults.js	85.71% <0.00%> (-14.29%)	⬇️

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