Applied some rector rules to update the code; Some formatting and sorting, too.
requested to merge issue/entity_translate_side_by_side-3418308:3418308-code-modernization into 1.0.x
- ConsistentImplodeRector (http://php.net/manual/en/function.implode.php#refsect1-function.implode-description)
- ClosureToArrowFunctionRector (https://wiki.php.net/rfc/arrow_functions_v2)
- ClassPropertyAssignToConstructorPromotionRector (https://wiki.php.net/rfc/constructor_promotion https://github.com/php/php-src/pull/5291)
- ChangeSwitchToMatchRector (https://wiki.php.net/rfc/match_expression_v2)
Closes #3418308