Add totalCount to relay API

### Is your proposal related to a problem?

We cannot use relay API and do pagination while still showing total number of matches.

### Describe the solution you'd like

Add `totalCount` to relay implementation. From https://graphql.org/learn/pagination/

```graphql
query friendsConnection(first:2 after:"Y3Vyc29yMQ==") {
totalCount
edges {
node {
name
}
cursor
}
pageInfo {
endCursor
hasNextPage
}
}
```

### Describe alternatives you've considered

Not using hasura relay API.

### If the feature is approved, would you be willing to submit a PR?

I don't have the knowledge to do so.

The issue names no repository files or tests; begin by locating the relay implementation and reviewing the linked GraphQL pagination example. Done means relay connections expose totalCount alongside edges and pageInfo, with coverage for the paginated query.

Written by the indexing model from the issue text.