Enhancement: Enable phpdoc_summary fixer

[localheinz]

This PR

• enables the phpdoc_summary fixer
• runs php-cs-fixer
• sorts out a few issues manually

Slightly related to #3936.

💁‍♂️ For reference, see https://github.com/FriendsOfPHP/PHP-CS-Fixer/tree/v2.16.3#usage:

phpdoc_summary

PHPDoc summary should end in either a full stop, exclamation mark, or question mark.

[codecov]

Codecov Report

Merging #4294 into master will decrease coverage by 0.02%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##             master    #4294      +/-   ##
============================================
- Coverage     84.67%   84.65%   -0.03%     
  Complexity     4551     4551              
============================================
  Files           257      218      -39     
  Lines         11428    11306     -122     
============================================
- Hits           9677     9571     -106     
+ Misses         1751     1735      -16     

Impacted Files	Coverage Δ	Complexity Δ
src/Framework/Constraint/Cardinality/IsEmpty.php	100.00% <ø> (ø)	7.00 <0.00> (ø)
src/Framework/Constraint/Constraint.php	100.00% <ø> (ø)	17.00 <0.00> (ø)
src/Framework/Constraint/Equality/IsEqual.php	100.00% <ø> (ø)	10.00 <0.00> (ø)
...work/Constraint/Equality/IsEqualCanonicalizing.php	62.96% <ø> (ø)	9.00 <0.00> (ø)
...mework/Constraint/Equality/IsEqualIgnoringCase.php	81.48% <ø> (ø)	9.00 <0.00> (ø)
...Framework/Constraint/Equality/IsEqualWithDelta.php	68.18% <ø> (ø)	7.00 <0.00> (ø)
src/Framework/Constraint/Exception/Exception.php	100.00% <ø> (ø)	6.00 <0.00> (ø)
...c/Framework/Constraint/Exception/ExceptionCode.php	100.00% <ø> (ø)	4.00 <0.00> (ø)
...ramework/Constraint/Exception/ExceptionMessage.php	100.00% <ø> (ø)	7.00 <0.00> (ø)
...nt/Exception/ExceptionMessageRegularExpression.php	100.00% <ø> (ø)	5.00 <0.00> (ø)
... and 138 more

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[localheinz]

Thank you, @sebastianbergmann!