Merge pull request #5119 from matrix-org/rav/admin_api_urls

changelog.d/5119.feature

docs/admin_api/account_validity.rst

docs/admin_api/delete_group.md

docs/admin_api/media_admin_api.md

docs/admin_api/purge_history_api.rst

docs/admin_api/purge_remote_media.rst

docs/admin_api/register_api.rst

docs/admin_api/user_admin_api.rst

docs/admin_api/version_api.rst

docs/sample_config.yaml

synapse/app/homeserver.py

synapse/config/server.py

synapse/rest/__init__.py

synapse/rest/admin/__init__.py

tests/handlers/test_user_directory.py

tests/push/test_email.py

tests/push/test_http.py

tests/rest/admin/__init__.py

tests/rest/admin/test_admin.py

tests/rest/client/test_consent.py