xF2 Add-on [tl] Watermark 2.0.4

Notable changes:

• Fixed warning message in PHP 8.
• Improvement check add watermark for user.

Notable changes:

• Added to support add watermark to specific contents

Notable changes:

• Fixed undefined index content

Notable changes:

• Allow user customize watermark text with right permission
• Bump add-on require XF 2.2.0 or higher

Notable changes:

• Added new permissions which allow user can turn off watermark
• Added option to control scale watermark image (width, height).