Add PHPStan

[divine]

Add PHPStan

Closes: #1930

Fixes will be added with another PR to keep everything simple as possible.

[codecov-commenter]

Codecov Report

Patch and project coverage have no change.

Comparison is base (af13eda) 90.57% compared to head (d503699) 90.57%.

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Additional details and impacted files

@@            Coverage Diff            @@
##             master    #2471   +/-   ##
=========================================
  Coverage     90.57%   90.57%           
  Complexity      748      748           
=========================================
  Files            34       34           
  Lines          1783     1783           
=========================================
  Hits           1615     1615           
  Misses          168      168           

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[Smolevich]

Maybe to mark as not required step

[Treggats]

@divine would you be ok with it if I continue'd your work with this PR?

[divine]

@divine would you be ok with it if I continue'd your work with this PR?

Hello,

Of course you can continue to work on this. Honestly, it's quite old PR, at that time there were like 300 errors that needed to be fixed, not sure how much is work currently is needed.

Thanks!

[Treggats]

@divine would you be ok with it if I continue'd your work with this PR?

Hello,

Of course you can continue to work on this. Honestly, it's quite old PR, at that time there were like 300 errors that needed to be fixed, not sure how much is work currently is needed.

Thanks!

The amount of work depends on the level. On level 5 there are around 64 issues and on level 9, which is the max, there are 384 errors.
But for now I've set it to level 2, with a baseline. So it would ignore certain errors. Makes it easier to ease in to fixing those.

[GromNaN]

Closing in favor of #2664