Remove priority mutex (#644)

* Removed hal::priority_condition_variable

* Replaced uses of priority mutexes with std::mutex and std::recursive_mutex

This allowed replacing a use of std::condition_variable_any with
std::condition_variable.

* Replaced all uses of std::recursive_mutex with std::mutex equivalents

hal/src/main/native/sim/DigitalInternal.cpp

@@ -11,7 +11,6 @@
 #include "HAL/AnalogTrigger.h"
 #include "HAL/HAL.h"
 #include "HAL/Ports.h"
-#include "HAL/cpp/priority_mutex.h"
 #include "PortsInternal.h"
 
 namespace hal {