Selecting multiple actors with differing DataTableHandles causes data loss

The data table customization (and probably others) tries to aggressively clear out row references that are not valid in the table they point to. This breaks when selecting multiple actors or objects that have different row handle values. It tries to look up the value but fails due to them being different, and then clears out the row because it thinks it is also bad.

No customizations should cause data loss from just viewing them, so this should be fixed to not fix up handles with multiple differing values. It should also be re-evaluated if the fixup code should run at all when the handle is just viewed

1. Create an actor blueprint with a Data Table Handle variable that is set to instance editable
2. Place two instances of that actor in the world, set the handle to point to different tables and rows
3. Select both actors at the same time, the row name switches to None
4. Select an individual actor, note that the row name is STILL none, which means that selecting actors actually causes data loss in this case