Replace StyleCI with PHP CS Fixer

[mspirkov]

Q	A
Is bugfix?	❌
New feature?	❌
Breaks BC?	❌
Fixed issues	comma-separated list of tickets # fixed by the PR, if any

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.37%. Comparing base (19e45d2) to head (28881a5).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master      #62      +/-   ##
============================================
+ Coverage     98.36%   98.37%   +0.01%     
  Complexity       47       47              
============================================
  Files             3        3              
  Lines           122      123       +1     
============================================
+ Hits            120      121       +1     
  Misses            2        2              

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