Power off control pin on Thinknode m5 during deepsleep and add RTC (#9510)

* Power off control pin on Thinknode m5 during deepsleep

* Apply suggestion from @Copilot

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Finish HAS_RTC cleanup

* Add RTC for Thinknode M5

* Don't double-init Wire

* Specify the RTC chip directly rather than use SensorRtcHelper.
Saves a bit of flash, and avoid mis-detection

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

src/platform/esp32/main-esp32.cpp

@@ -24,6 +24,11 @@
 #include <nvs.h>
 #include <nvs_flash.h>
 
+// Weak empty variant shutdown prep function.
+// May be redefined by variant files.
+void variant_shutdown() __attribute__((weak));
+void variant_shutdown() {}
+
 #if !defined(CONFIG_IDF_TARGET_ESP32S2) && !MESHTASTIC_EXCLUDE_BLUETOOTH
 void setBluetoothEnable(bool enable)
 {
@@ -249,6 +254,7 @@ void cpuDeepSleep(uint32_t msecToWake)
 
 #endif // #end ESP32S3_WAKE_TYPE
 #endif
+    variant_shutdown();
 
     // We want RTC peripherals to stay on
     esp_sleep_pd_config(ESP_PD_DOMAIN_RTC_PERIPH, ESP_PD_OPTION_ON);