Add a watchdog module to meshsolar. (#9337)

* add watchdog module

* Restore the code in power.h

---------

Co-authored-by: Ben Meadors <benmmeadors@gmail.com>

src/watchdog/watchdogThread.h

@@ -0,0 +1,19 @@
+#pragma once
+
+#include <stdint.h>
+#include "concurrency/OSThread.h"
+
+#ifdef HAS_HARDWARE_WATCHDOG
+class WatchdogThread : private concurrency::OSThread
+{
+  public:
+
+    WatchdogThread();
+    void feedDog(void);
+    virtual bool setup();
+    virtual int32_t runOnce() override;
+
+};
+
+extern WatchdogThread *watchdogThread;
+#endif