Function getCurrentNanosecondsSinceEpoch

unittests/catch.hpp:10528–10530

namespace Catch {

    auto getCurrentNanosecondsSinceEpoch() -> uint64_t {
        return std::chrono::duration_cast<std::chrono::nanoseconds>( std::chrono::high_resolution_clock::now().time_since_epoch() ).count();
    }

    auto estimateClockResolution() -> uint64_t {
        uint64_t sum = 0;