[bug] FilterSerializerByOrganization filters fields without organization

[pandafy]

FilterSerializerByOrganization filters queryset of all related fields using the organization_lookup. But, it might be possible that a model does not have relation to Organization (not even an indirect one, e.g. WiFiClient in openwisp-monitoring).

We should allow to exclude fields from the organization filtering.

[nemesifier]

@Aryamanz29 do you think this was fixed by 670ec93 ?

[Aryamanz29]

@Aryamanz29 do you think this was fixed by 670ec93 ?

@nemesifier I don't think this issue has been addressed, and I believe it remained unresolved during the development of multitenant capabilities for the Django Filters feature. This happened because we decided to complete that PR only for the Wi-Fi session REST API. Previously, we were also working on adding a REST API for Wi-Fi clients, and it was during that time that we encountered this bug.