horsegen: generate koka id lists as public

horsegen/scenario.kk.template

@@ -12,7 +12,7 @@ extern create-id-table(): vector<int>
   c inline "int32_t arr[] = { {{- range $s := $.Scenarios }}{{ $s.ID }},{{ end -}} };\nkk_vector_from_cint32array(arr, (kk_ssize_t){{ $.ScenarioCount }}, kk_context())"
   js inline "[{{ range $s := $.Scenarios }}{{ $s.ID }},{{ end }}]"
 // Vector of all scenario IDs in order for easy iterating.
-val all = once(create-id-table)
+pub val all = once(create-id-table)
 
 // Get the name for a scenario.
 // If no scenario matches the ID, the result contains the numeric ID.