Fix GetKeyPressed for PLATFORM_DESKTOP_SDL (#3869)

The key handling in PLATFORM_DESKTOP_SDL was faulty in two ways, which
led to GetKeyPressed returning incorrect data.

CORE.Input.Keyboard.keyPressedQueue was updated only on SDL_TEXTINPUT,
meaning only text characters were registered as a pressed key, but not
function keys (eg. tab, backspace...). Also on such event, both
CORE.Input.Keyboard.keyPressedQueue and
CORE.Input.Keyboard.charPressedQueue were assigned the key's
corresponding codepoint, when CORE.Input.Keyboard.keyPressedQueue
should get the raylib keycode instead.

CORE.Input.Keyboard.keyPressedQueue is now updated on SDL_KEYDOWN event
instead.

Co-authored-by: Arthur <hi@thenightwat.ch>

src/platforms/rcore_desktop_sdl.c

@@ -1131,7 +1131,17 @@ void PollInputEvents(void)
             case SDL_KEYDOWN:
             {
                 KeyboardKey key = ConvertScancodeToKey(event.key.keysym.scancode);
-                if (key != KEY_NULL) CORE.Input.Keyboard.currentKeyState[key] = 1;
+
+                if (key != KEY_NULL) {
+                    // If key was up, add it to the key pressed queue
+                    if ((CORE.Input.Keyboard.currentKeyState[key] == 0) && (CORE.Input.Keyboard.keyPressedQueueCount < MAX_KEY_PRESSED_QUEUE))
+                    {
+                        CORE.Input.Keyboard.keyPressedQueue[CORE.Input.Keyboard.keyPressedQueueCount] = key;
+                        CORE.Input.Keyboard.keyPressedQueueCount++;
+                    }
+
+                    CORE.Input.Keyboard.currentKeyState[key] = 1;
+                }
 
                 if (event.key.repeat) CORE.Input.Keyboard.keyRepeatInFrame[key] = 1;
 
@@ -1154,14 +1164,6 @@ void PollInputEvents(void)
 
                 int codepointSize = 0;
 
-                // Check if there is space available in the key queue
-                if (CORE.Input.Keyboard.keyPressedQueueCount < MAX_KEY_PRESSED_QUEUE)
-                {
-                    // Add character (key) to the queue
-                    CORE.Input.Keyboard.keyPressedQueue[CORE.Input.Keyboard.keyPressedQueueCount] = GetCodepointNext(event.text.text, &codepointSize);
-                    CORE.Input.Keyboard.keyPressedQueueCount++;
-                }
-
                 // Check if there is space available in the queue
                 if (CORE.Input.Keyboard.charPressedQueueCount < MAX_CHAR_PRESSED_QUEUE)
                 {