refactor: sdl3::events - Modernize/Update SDL3 Events

[marstaik]

Hi, while using migrating from winit to SDL3, I noticed that some of the events strangely did not have all of the correct fields and names (In my particular case, I have multiple windows and many of the events were missing window_id).

Seeing as some of these events haven't been updates in years from their source, I went ahead and modernized the events a bit. Thankfully, as you can see in the examples, their replacement/updated usage is pretty easy to follow.

Key changes:

• Group related raw SDL events under category enums (Window, Keyboard, Mouse, Joystick, Controller, etc.).
• Preserve ability to convert to/from raw SDL_Event (where feasible).
• Keep the name Event so external code continues to reference crate::event::Event.
• Maintain custom/user event registration and pushing.
• Provide helper methods analogous to the old API (get_timestamp, get_window_id, is_* classifiers).

[revmischa]

Thank you! Happy to look/merge when CI is passing 😄

[marstaik]

Yep, working on it, I missed some of them because of the feature flags

[marstaik]

I am considering adding a lifetime to events so that we can avoid cloning into Strings. If we add a lifetime bound to the event pump, since SDL handles backing memory we should be gracefully be able to just have CStr, and let the user decide when to allocate. I think its a better solution than just copying payloads.

Since a vast majority of the events don't have string references, the inner types should be trivially copyable anyways if you really need a copy.

This would facilitate better to_ll/from_ll behavior, but I'm wondering if we really need to_ll still...

[revmischa]

Okay, please let me know when this PR is ready to merge. Do you want to add lifetimes here or later?