Add Grafana access review connector support

Add Grafana as an access review connector-backed source.

This introduces a Grafana access-review driver, provider registration,
and connector settings for the Grafana base URL. It also wires the
new provider through GraphQL and access-review UI input mapping so
API-key connectors can be created from the product.

A connector_provider enum migration is included so Grafana can be
persisted in existing databases.

Signed-off-by: Cursor Agent <cursoragent@cursor.com>

Co-authored-by: Bryan FRIMIN <bryan@frimin.fr>

pkg/coredata/connector_settings.go

@@ -39,6 +39,10 @@ type (
 		OrganizationSlug string `json:"organization_slug"`
 	}
 
+	GrafanaConnectorSettings struct {
+		BaseURL string `json:"base_url"`
+	}
+
 	SupabaseConnectorSettings struct {
 		OrganizationSlug string `json:"organization_slug"`
 	}