Replace StyleCI with PHP CS Fixer

[mspirkov]

Q	A
Is bugfix?	❌
New feature?	❌
Breaks BC?	❌

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (d9a1507) to head (31108dc).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff             @@
##              master      #220   +/-   ##
===========================================
  Coverage     100.00%   100.00%           
  Complexity        48        48           
===========================================
  Files              4         4           
  Lines            103       104    +1     
===========================================
+ Hits             103       104    +1     

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