This reverts commit 3cbd6cef.

This function is used when content upgrade is run. The function
was originally public static, but changed into a private instance
function. Reason for this was unknown.

This will show requirements in status report, and make it much more visible.
Added translatable texts for the requirements.

A lot of support requests are connected to not setting up PHP correctly. This should mitigate some of the requests.

This should fix the error when trying to delete nodes
with interactive content fields.