Make phpdoc tags configurable

We introduced legacy class name migration for phpdoc tags in #2. The tags are hardcoded in our code: https://github.com/DanielSiepmann/automated-typo3-update/pull/2/files#diff-ca39e5d97cbcfc94da8e8e787e0d4c3eR35

By making them public they are configurable through ruleset.xml.