Overhaul CI tests

[christianlupus]

Closes #537

The test environment is updated and enhanced to allow better integration testing

• Make the run-local.sh script command line parameter aware
• Trigger pulls/builds from docker explicitly
• Build a docker image to use as a basis for integration tests
• Better structure the file for better understandability, define useful chunks of functionality
• Prepare integration testing using docker + phpunit + setup (bash) script
• [optional] Build a daily/weekly set of prebuilt docker images on the docker hub for faster test setup (only the dependencies)
• [optional] run the test routines in a docker container in order to have the same commands on GH actions and locally (?)
• Allow tests also for unsupported NC versions
• Update documentation for testing

[codecov]

Codecov Report

Merging #564 (217ff45) into master (10178b2) will increase coverage by 0.00%.
The diff coverage is n/a.

@@           Coverage Diff            @@
##             master    #564   +/-   ##
========================================
  Coverage      1.01%   1.01%           
  Complexity      440     440           
========================================
  Files            13      13           
  Lines          1381    1379    -2     
========================================
  Hits             14      14           
+ Misses         1367    1365    -2     

Flag	Coverage Δ	Complexity Δ
integration	0.00% <ø> (ø)	0.00 <ø> (ø)
unittests	1.01% <ø> (+<0.01%)	0.00 <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ	Complexity Δ
lib/Controller/ConfigController.php	0.00% <0.00%> (ø)	7.00% <0.00%> (ø%)

[christianlupus]

I will merge this now. I hope it is working as assumed but if errors arise, we will have to tackle them in time.