Add SigNoz access review driver

Add a SigNoz connector so its organization members can be pulled into
access-review campaign snapshots. SigNoz authenticates with a
SIGNOZ-API-KEY admin service-account key and a customer-supplied base
URL (a SigNoz Cloud region/tenant host or a self-hosted instance).

The driver lists users via GET /api/v1/user, which returns the role
(ADMIN/EDITOR/VIEWER) inline so admin detection works in a single call,
and maps the SigNoz user status (active / pending_invite / deleted) to
the account active flag. The name resolver reads the organization
display name from GET /api/v2/orgs/me to title the access source.

Wire the provider through the coredata enum and settings, the
connector-provider registry (driver and name-resolver factories), the
console API-key input schema and validation, the access-review source
label, and the SigNoz brand logo.

Co-authored-by: Bryan FRIMIN <bryan@frimin.fr>
Signed-off-by: Aurélien Sibiril <81782+aureliensibiril@users.noreply.github.com>

pkg/coredata/connector_settings.go

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