HAL/LL: Generic EXTI & trainer driver

Changes:
- generic EXTI driver
- generic trainer driver
- relocated rotary encoder timer (simple 100us delay) from TIM4 to TIM12
- taranis & horus use now TIM4 for trainer pulses
- serial driver handles periph clocks for UARTs

TODO:
- SBUS on heartbeat pin (USART or soft-serial)

radio/src/targets/simu/module_drivers.cpp

@@ -44,12 +44,12 @@ void extmoduleSendNextFramePxx1(void const*, unsigned short) {}
 void extmoduleSendNextFrameSoftSerial(void const*, unsigned short, bool) {}
 void extmoduleSendNextFramePpm(void*, unsigned short, unsigned short, bool) {}
 
-#if defined(TRAINER_GPIO)
 void init_trainer_ppm() {}
 void stop_trainer_ppm() {}
 void init_trainer_capture() {}
 void stop_trainer_capture() {}
-#endif
+
+bool is_trainer_connected() { return false; }
 
 void init_trainer_module_cppm() {}
 void stop_trainer_module_cppm() {}