Establish TYPO3 12.4 compatibility

Various updates to make this Extension TYPO3 12 compatible

Official TYPO3 9.5 support

• Official TYPO3 9.5 support
• Added a finisher for EXT:form
• support for custom directory for the keyring
• Added Documentation
• code cleanup
• made signing optional
• deprecated older versions
• Version bump

Compability with 9.4

Tested with TYPO3 9.4 Backend