FIX Update "OwnerClassName" on the EA when necessary (#816)
FIX Update "OwnerClassName" on the EA when necessary (#816)

Fix for when the "OwnerClassName" needs updating in the EA

Otherwise when you change `PageType` it can cause issues with retrieving
the Elements for the page

Co-authored-by: Lee Bradley <3ad6fe24eb74b3cd10be8be1e7293c24a45629e0@made.media>
dnadesign/silverstripe-elemental,dnadesign/silverstripe-elemental