src: use smart pointer instead of new and delete

Use an std::unique_ptr for variables that are deleted
right after creation.

Since the destructor of InspectorTimer is private
but needed by the unique_ptr, define deleter_type as friend.

PR-URL: https://github.com/nodejs/node/pull/17020


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Timothy Gu <timothygu99@gmail.com>