add support for hid gamepad interface

add documentation for HID joystick
Add joystick_task to read analog axes values even when no key is pressed or release. update doc
Update docs/feature_joystick.md
Manage pin setup and read to maintain matrix scan after analog read

quantum/process_keycode/process_joystick.h

@@ -0,0 +1,13 @@
+#ifndef PROCESS_JOYSTICK_H
+#define PROCESS_JOYSTICK_H
+
+#include <stdint.h>
+#include "quantum.h"
+
+bool process_joystick(uint16_t keycode, keyrecord_t *record);
+
+void joystick_task(void);
+
+bool process_joystick_analog(void);
+
+#endif //PROCESS_JOYSTICK_H