Modernize codebase to ES2015+

After dropping support for Node.js 4 (NODEJS-516), given that Node.js 6 supports 95%+ of the features in the spec, we can modernize the driver codebase by:

• Using Object destructuring for require.

• Use rest parameters.

• Use spread syntax.

• Migrate to class syntax to the few constructor and prototype declarations left, like Connection and ControlConnection, Protocol and Parser.

• Use Array.prototype.includes()

• ...