Removed SDL_HasGamepads(), SDL_HasJoysticks(), and SDL_HasSensors()

Also cleaned up logic for whether we need to poll for events:
- We need to periodically poll for joysticks to handle hotplug.
- We need to frequently poll for joysticks and sensors when they're open so their state can be updated

include/SDL3/SDL_sensor.h

@@ -128,17 +128,6 @@ typedef enum
 
 /* Function prototypes */
 
-/**
- * Return whether there are sensors connected
- *
- * \returns SDL_TRUE if there are sensors connected, SDL_FALSE otherwise.
- *
- * \since This function is available since SDL 3.0.0.
- *
- * \sa SDL_GetSensors
- */
-extern DECLSPEC SDL_bool SDLCALL SDL_HasSensors(void);
-
 /**
  * Get a list of currently connected sensors.
  *