[Feature]: Support nb_inventory when netbox is exposed on a subpath

[alexandrud]

NetBox version

v4.0.6

Feature type

Change to existing Plugin

Proposed functionality

The issue is described in #1195.
Currently if you install netbox on a subpath "/netbox" the inventory plugin will not work. Adapt the plugin so we can configure the endpoint with a subpath: "https://example.com/netbox".

Use case

There are situations where we want netbox on a subpath rather than "/". Especially in cases where we want to stack multiple applications installed in a kubernetes cluster on the same FQDN.

External dependencies

No response