Add custom links to device components

[JulianJacobi]

Environment

• Python version: 3.7
• NetBox version: 2.10.4

Proposed Functionality

Add custom links to interfaces.

Use Case

We use custom links to linking to our grafana dashboards directly out of Netbox. So to link to interface-detail dashboards it would be very nice to have custom links at interfaces as well.

Database Changes

None

External Dependencies

None

[jeremystretch]

Bumped the scope to include all device components. This should be fair game for a 2.10 release.