Provide hierarchical app config GraphQL queries

## Overview

Enable querying app configurations at different hierarchy levels (domain, project, user) with proper inheritance handling.

## Goals

- Add domain-level app config query
- Add project-level app config query
- Add user-level app config query
- Support configuration inheritance across levels

## Success Criteria

- Each hierarchy level has dedicated GraphQL query
- Configuration inheritance works correctly
- Users can query configs at appropriate access levels

JIRA Issue: BA-4113