Camera bookmark modifications are not saved unless it is a new bookmark

This is not a regression. Tested in //UE5/Release-5.0 cl20979098.

Camera bookmark modifications are not saved unless it is a new bookmark.

From the user reporter:
"FBookmarkTypeToolsImpl.CreateOrSetBookmark appears to be the only area of the bookmark code that calls Bookmark->Modify to mark the package dirty. and this code path is only when a new bookmark is created. If a bookmark of the appropriate type already exists in that slot, Modify does not get called, even though higher up the callstack, the bookmark is updated with the new view location"

1. Create or open any project
2. Create 2 levels
3. In the first level move the Camera
4. Press Ctrl+1 to bookmark the Camera's position then save
5. Open the second level
6. Reopen the first level then press 1 to move to the Bookmark
7. Move the camera to a new position then press Ctrl+1 to change the bookmark position
8. Save then open the second map
9. Open the first map
10. Press 1

Expected Results:
The camera moves to the updated book marked position from step 7

Actual Results:
The camera moves to the original book marked position from step 4