Implements Per Resource Events notifications in Node Solid Server.

Implementation Notes:
+ Uses `--experimental-require-module` to load esm packages natively. Requires node > 22.0.0. Start scripts and test invocations have been appropriately modified.
+ NSS converts strings into an older streaming format which was not being detected by Express-PREP. Express-PREP was modified to ask the user if the body provided is a stream, thus circumventing this issue.
+ Notifications are triggered from a common middleware, which is invoked after the response has been succesfully sent.
+ Uses Express PREP supplied default template for notifications.

Add Solid/Activity Streams format notifications:
+ Provides notifictions in JSON-LD and Turtle.
+ Extends notifications to PUT and POST methods.
+ Add Event-ID header field to the response of a write method.