Issue #3015697 by alexpott, andypost: Properly deprecate COMMENT_ANONYMOUS_* constants

core/modules/comment/src/CommentAccessControlHandler.php

core/modules/comment/src/CommentForm.php

...odules/comment/src/Plugin/Field/FieldType/CommentItem.php

.../Validation/Constraint/CommentNameConstraintValidator.php

...les/comment/tests/src/Functional/CommentAnonymousTest.php

...dules/comment/tests/src/Functional/CommentNonNodeTest.php

...dules/comment/tests/src/Kernel/CommentFieldAccessTest.php

...odules/comment/tests/src/Kernel/CommentValidationTest.php

...odules/rdf/tests/src/Functional/CommentAttributesTest.php