Adds a new Prometheus metric `coderd_db_query_counts_total` that tracks
the total number of queries by route, method, and query name. This is
aimed at helping us track down potential optimization candidates for
HTTP handlers that may trigger a number of queries. It is expected to be
used alongside `coderd_api_requests_processed_total` for correlation.
Depends upon new middleware introduced in
https://github.com/coder/coder/pull/21498
Relates to https://github.com/coder/internal/issues/1214