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 (d68b1b2) to head (0c9001b).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff             @@
##              master       #55   +/-   ##
===========================================
  Coverage     100.00%   100.00%           
  Complexity        69        69           
===========================================
  Files             17        17           
  Lines            161       174   +13     
===========================================
+ Hits             161       174   +13     

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