refactor: return template_icon and make metadata required (#16496)

coderd/database/queries/provisionerjobs.sql

@@ -136,6 +136,7 @@ SELECT
 	t.id AS template_id,
 	COALESCE(t.name, '') AS template_name,
 	COALESCE(t.display_name, '') AS template_display_name,
+	COALESCE(t.icon, '') AS template_icon,
 	w.id AS workspace_id,
 	COALESCE(w.name, '') AS workspace_name
 FROM
@@ -165,6 +166,7 @@ GROUP BY
 	t.id,
 	t.name,
 	t.display_name,
+	t.icon,
 	w.id,
 	w.name
 ORDER BY