Do not warn about a data file "not being part of a platform" if the file is inherited from another item

[Nicklas Nordborg]

For bioassays that have "Data files" linked to them, the table on the single-item view will display those files and warn if the linked file is of a type that has not been registered as related type to the bioassay item.

This table also list files that belong to parent items and in most cases this will cause a warning to be displayed: This file is not part of the xxx subtype. This warning makes no sense since it is comparing things that are not directly related.

[Nicklas Nordborg]

In 8137:

Fixes #2300: Do not warn about a data file "not being part of a platform" if the file is inherited from another item