Alerting: Add rule_matcher filter to Prometheus rules API (#115297)

**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>

pkg/services/ngalert/api/tooling/definitions/prom.go

@@ -462,4 +462,10 @@ type GetGrafanaRuleStatusesParams struct {
 	// in: query
 	// required: false
 	Matchers []string `json:"matcher"`
+
+	// Filter rules by their static labels (not alert instance labels). Each value is a JSON-encoded Prometheus-like matcher (for example, {"type":0,"name":"severity","value":"critical"}).
+	// For equality matchers with empty string values (e.g., name=""), rules that have the label with an empty value OR rules without the label will match (standard Prometheus behavior).
+	// in: query
+	// required: false
+	RuleLabelMatchers []string `json:"rule_matcher"`
 }