feat(enums): Add support for enums (#3283741 by chfoidl, claudiu.cristea, pfrenssen)

...r_sniffer/Drupal/Sniffs/Classes/ClassDeclarationSniff.php

coder_sniffer/Drupal/Sniffs/Classes/ClassFileNameSniff.php

coder_sniffer/Drupal/Sniffs/Classes/UseGlobalClassSniff.php

coder_sniffer/Drupal/Sniffs/Commenting/ClassCommentSniff.php

coder_sniffer/Drupal/Sniffs/Commenting/FileCommentSniff.php

...r_sniffer/Drupal/Sniffs/Commenting/InlineCommentSniff.php

...r/Drupal/Sniffs/Commenting/InlineVariableCommentSniff.php

coder_sniffer/Drupal/Sniffs/InfoFiles/ClassFilesSniff.php

..._sniffer/Drupal/Sniffs/Methods/MethodDeclarationSniff.php

coder_sniffer/Drupal/Sniffs/Scope/MethodScopeSniff.php

tests/Drupal/Commenting/FileCommentUnitTest.13.inc

tests/Drupal/Commenting/FileCommentUnitTest.13.inc.fixed

tests/Drupal/Commenting/FileCommentUnitTest.php

tests/Drupal/bad/BadUnitTest.php

tests/Drupal/bad/bad.php

tests/Drupal/bad/bad.php.fixed

tests/Drupal/good/good.php