RPC returning table alias now works for pg 11/12 (#2737)

The new LATERAL query used for calling the function, introduced on
https://github.com/PostgREST/postgrest/pull/2677, failed on functions
that returned a domain like `CREATE DOMAIN projects_domain AS projects`.

Work around that by changing the query conditionally, by
obtaining a bool that represents the composite alias on the SchemaCache
and only do this on pg 11 and 12.

src/PostgREST/App.hs

@@ -198,7 +198,7 @@ handleRequest AuthResult{..} conf appState authenticated prepared pgVer apiReq@A
 
     (ActionInvoke invMethod, TargetProc identifier _) -> do
       cPlan <- liftEither $ Plan.callReadPlan identifier conf sCache apiReq invMethod
-      resultSet <- runQuery (Plan.crTxMode cPlan) $ Query.invokeQuery (Plan.crProc cPlan) cPlan apiReq conf
+      resultSet <- runQuery (Plan.crTxMode cPlan) $ Query.invokeQuery (Plan.crProc cPlan) cPlan apiReq conf pgVer
       return $ Response.invokeResponse invMethod (Plan.crProc cPlan) apiReq resultSet
 
     (ActionInspect headersOnly, TargetDefaultSpec tSchema) -> do