**What is this feature?**
Add `rule_matcher` filter to the Prometheus-compatible list rules API: `/api/prometheus/grafana/api/v1/rules`. It allows to filter rules by static labels (not by alert instance labels).
**Special notes:**
- Equality (`=`) and inequality (`!=`) matchers are pushed down to the database. Regex matchers (`=~`, `!~`) are applied in-memory at the API layer.
- SQLite: Uses GLOB pattern matching
- MySQL / PostgreSQL: Use JSON functions to compare label values
---------
Co-authored-by: Konrad Lalik <konradlalik@gmail.com>
Alexander Akhmetov
