Interfaces API endpoint does not allow filtering by multiple device slugs

[lampwins]

Environment

• Python version: 2.6.8-dev
• NetBox version: 3.7

Steps to Reproduce

1. Create two devices named device-1 and device-2
2. Create interfaces on each of those devices
3. Attempt to filter the /api/dcim/interfaces/ endpoint by both the device names. i.e. /api/dcim/interfaces/?device=device-1&device=device-2

Expected Behavior

The result set to include all interfaces from both devices.

Observed Behavior

Only those interfaces belonging to device-2 are returned. This is because device-2 is listed last in the query param filter.

The root cause is the InterfaceFilter uses a method for the device field which does not accept multiple values.

https://github.com/netbox-community/netbox/blob/develop/netbox/dcim/filters.py#L750