Add support in the ci for phpstan

Descriptive title for this enhancement

we need to add static code analysis to our ci with phpstan

Actual behavior

we only run php lint et code sniffer on our code actually

Expected behavior

find error by running code analysis on our code

Step by step description of new behaviour

1. copy the .neon file from https://gitlab.fusiondirectory.org/fusiondirectory/dev-tools/-/tree/master/phpstan/fusiondirectory/1.4-dev into the root of the core source
2. run phpstan -c phpstan.neon

Benefits

get static analysis of the code

Possible Drawbacks

none

Applicable Issues

assigned to @bmortier

changed milestone to %FusionDirectory 1.4

added gitlab-ci label

added PJ1802-0188 label

assigned to @cchilliet and unassigned @bmortier

changed due date to August 02, 2021

mentioned in commit 0477b9ed

mentioned in commit 878e7b0b

mentioned in commit cc25d15c

added 2h of time spent

mentioned in commit 727535a4

added 5h of time spent

mentioned in commit 3296dadd

closed

added 1h of time spent