[rcore] Add basic support for scancodes

[JeffM2501]

Currently raylib does not expose the scancode data for keyboard input received from the platform. This makes it VERY hard to build keyboard bindings that work with different keyboard mappings and localizations. They KeyboardKey enum is just the physical keys and does not take the keyboard mapping into account. For most game input this is fine, as you want the physical key, but there are use cases where you need local mapping of non-text keys.

GetCharPressed handles the mapping, but only for printable characters.

Any user that wants the 'logical' key that is provided by the keyboard mapping as no way to get this data.
The data was passed to the keyboard input functions of most platforms, but the raylib key system has no place to store it.
In SDL this scancode is the 'virtual key'

This PR adds GetKeyPressedPro that takes an optional scancode to fill out, allowing people to see the localized key for each event.
Platforms that don't provide a scancode set the code to -1.

I don't know if this should go into 5.5 or if we should discuss the API for the future. This is just the smallest possible change to raylib to expose the data that it's currently ignoring. I am just posting this so it doesn't get lost.

[raysan5]

@JeffM2501 I see the issue but I want to review this change more carefully, waiting after 5.5 release for further discussion.

[JeffM2501]

@JeffM2501 I see the issue but I want to review this change more carefully, waiting after 5.5 release for further discussion.

Absolutely understandable