Write a file `uuid` in server's data directory that contains random UUID, generated at startup if file does not exist.

It will be used for several purposes:
- to anonymously identify server in Sentry (currently Sentry is unusable);
- (possible future usage) to identify server in ensemble.

@tavplubix comments?
#if USE_UNWIND && !WITH_COVERAGE && !defined(SANITIZER) && defined(__x86_64__)
    
    if (hasPHDRCache())
    {
        global_context->initializeTraceCollector();
        
        UInt64 total_memory_profiler_step = config().getUInt64("total_memory_profiler_step", 0);
        if (total_memory_profiler_step)
        {
            total_memory_tracker.setOrRaiseProfilerLimit(total_memory_profiler_step);
            total_memory_tracker.setProfilerStep(total_memory_profiler_step);
        }
        double total_memory_tracker_sample_probability = config().getDouble("total_memory_tracker_sample_probability", 0);
        if (total_memory_tracker_sample_probability)
        {
            total_memory_tracker.setSampleProbability(total_memory_tracker_sample_probability);
        }
    }
#endif
    
#if !USE_UNWIND
    LOG_INFO(log, "Query Profiler and TraceCollector are disabled because they cannot work without bundled unwind (stack unwinding) library.");
#endif
#if WITH_COVERAGE
    LOG_INFO(log, "Query Profiler and TraceCollector are disabled because they work extremely slow with test coverage.");
#endif