Show Used by registries column on maven upstreams list view

Context

We want to show the number of registries an upstream is shared with.

Design

#556837[UpstreamsList.png]

Proposal

Add Used by registries column to the upstreams list table.

Implementation

1. We can get the registries count from the GraphQL API being added in Add group field to query all maven virtual regi... (!205320)
2. For 1, we need to replace the existing REST API with GraphQL API & update the pagination.