GraphQL API: Add a way to negate conditions in the runner search

In !61174 (merged) we introduced a way for users to find runners using the GraphQL API, we should extend this API with NOT operators.

The HAML implementation of the runners allows users to use NOT operators (!=) when filtering their runners.

NOT operators for all filters

This should be ported to the new GraphQL runner filters.

Our GraphQL uses the "negated" inputs when filtering issues, epics, etc...:

Edited May 21, 2021 by Miguel Rincon