Use atomic inside YARP

[Nicogene]

During the refactoring done for the release of YARP 3.0.0 @drdanz and me found that yarp is plenty of code like this

class Foo 
{
   int count;
   std::mutex;
   void doStuff()
   {
       mutex.lock();
       count++;
       mutex.unlock();
   }
};

that should become

class Foo 
{
   std::atomic<int> count;
   void doStuff()
   {
       count++;
   }
};

atomic will free us from a lot of mutexes/semaphores

[barbalberto]

For boolean flags (bool only) there is also std::atomic_flag which is atomic and lock-free

From https://en.cppreference.com/w/cpp/atomic/atomic_flag

std::atomic_flag is an atomic boolean type. Unlike all specializations of std::atomic, it is guaranteed to be lock-free.