GraphQL : Add custom fields as filter arguments

[dgarros]

Environment

• Python version: 3.7
• Nautobot version: 1.0.0b2

Proposed Functionality

Add support for custom fields in filter argument for all graphql types
Currently it's possible to define some arguments when querying a model, at the top level, but it's not possible to query by custom fields.

if there is a custom field type defined under Site model, it should be possible to search for cf_type

{
  sites(cf_type: "ams") {
	id
        name
}

Use Case

Similar to the API, it would be good to be able to search by custom fields with cf_<custom_field_name>

Database Changes

No

External Dependencies

No

[jathanism]

Fixed in #246