Add low-level hook for SDL3 input events

[Ivan1pl]

Resolves #2864

[gemini-code-assist]

Code Review

This pull request introduces the SdlEventListener interface to allow custom listeners to receive raw SDL events, and updates SdlJoystickInput, SdlKeyInput, and SdlMouseInput to implement it. LwjglWindow is updated to manage these listeners and dispatch events. The feedback suggests wrapping the custom listener event dispatch loop in a try-catch block to prevent any unhandled exceptions from interrupting the dispatching of events to subsequent listeners and internal input handlers.

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[capdevon]

I wonder if registerSdlEventListener(...) could be renamed to addSdlEventListener(...) for consistency with removeSdlEventListener(...).

Using complementary method pairs (add/remove, get/set, etc.) is a well-established Java API convention and tends to make APIs more intuitive. Since the method simply adds the listener to an internal collection, addSdlEventListener() also seems to better reflect what it actually does.

[Ivan1pl]

True. I went for consistency with existing API for WindowSizeListener: registerWindowSizeListener and removeWindowSizeListener. With that in mind, should I rename this to addSdlEventListener, or keep it as it is?

[capdevon]

You're right, and I owe you an apology for assuming your suggestion was inconsistent with the existing API. Your reply made it clear that you were actually following the current WindowSizeListener naming (registerWindowSizeListener / removeWindowSizeListener).

At this point, I see two possible approaches:

1. Adopt the add/remove convention for new APIs. In that case, this PR could introduce addSdlEventListener() / removeSdlEventListener(), and a follow-up PR could deprecate registerWindowSizeListener() in favor of addWindowSizeListener(), while keeping backward compatibility for the time being.

2. Keep consistency with the existing API. That would mean naming the new methods registerSdlEventListener() / removeSdlEventListener(), matching the current WindowSizeListener API even though the register/remove pairing is less consistent with common Java naming conventions.

That said, this is only my opinion. The final decision on API direction should rest with the engine maintainers.
@riccardobl