lib: remove inherits() usage

This switches all `util.inherits()` calls to use
`Object.setPrototypeOf()` instead. In fact, `util.inherits()` is
mainly a small wrapper around exactly this function while adding
the `_super` property on the object as well.

Refs: #24395

PR-URL: https://github.com/nodejs/node/pull/24755
Refs: https://github.com/nodejs/node/issues/24395
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>

lib/https.js

@@ -149,7 +149,7 @@ function Agent(options) {
     list: []
   };
 }
-inherits(Agent, HttpAgent);
+Object.setPrototypeOf(Agent.prototype, HttpAgent.prototype);
 Agent.prototype.createConnection = createConnection;
 
 Agent.prototype.getName = function getName(options) {