Create multiQuery middleware

src/libs/middlewares/multiQuery.js

+const libs = `${process.cwd()}/libs`;
+const log = require(`${libs}/log`)(module);
+const db = require(`${libs}/db/query_exec`);
+
+// Middleware that executes multiples queries 
+function multiQuery(req, res, next) {
+    Promise.all(db.execMultiQuery(req.querySet)).then((queryResults) => {
+        req.result = queryResults;
+        next();
+    }).catch((err) => {
+        log.error(`[SQL query error] ${err}`);
+        next(err);
+    });
+}
+
+module.exports = multiQuery;