Adds warning similar to 5.57 if Activity Revisions are present.

Adds warning similar to 5.57 if Activity Revisions are present.

Checks if upgrade is from version after 5.57.alpha1

If so check for any activities which are not the current revision

Issue warning.

Notes:
- Doesn't check if Foreign Key on delete trigger was updated to prevent
  deletion
- Doesn't warn about the above - we assume this is covered in the steps
  people will follow in the link - or that they will have done this
  already.