Allow configuring the default cookie category when blocking iframes

This should be now ready for review.

The basic functionality works and it also adds support for custom iframe blocking if the needed data attributes are already available in the iframe. In this case the iframe blocking logic is skipped.

I also added context to all module translated strings because they were missing from all t() functions. This should be mentioned in the change log when we release the next version.

After this is merged we can continue with ✨ Allow the administrator to define the message and button text for blocking iframes Active . We need to decide how we can support the dynamic cookie category in the iframe functionality and custom message with translation support. Perhaps we can for example separate the general message that can be customized from the category information.

Looks fine to me. I have reviewed the code quite thoroughly with Heikki.

Automatically closed - issue fixed for 2 weeks with no activity.