Implement EventCollector and typical events

Problem/Motivation

To track typical events, we should follow the way google_tag implements the event tracking:
https://git.drupalcode.org/project/google_tag/-/tree/2.0.x/src?ref_type=...

Implement

• EventCollector
• EventCollectorInterface
• EventSubscriber/*

I'm not yet sure, which way we go then for the definition of events.

In posthog_php_events.module we already have some hooks, which we can't track through Events (as they don't exist as events).

https://git.drupalcode.org/project/google_tag/-/blob/2.0.x/google_tag.mo... has further events and implements some events differently, not yet sure which is the better approach.

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes