CDeviceUtils::ConvertToString() is error-prone

[marktsuchida]

It uses a common static buffer, so it is (1) not thread-safe and (2) error-prone even when used in only one thread.

For example, what this code will print is up to the whim of the compiler:

mmCoreAndDevices/DeviceAdapters/Modbus/ModbusModule.cpp

Line 185 in 1aa373b

LogMessage(string("Trying to perform a rtu connection via ") + conuri.hostandaddress + " baud: " + CDeviceUtils::ConvertToString(baud) + " parity: " + parityChars + " data_bit: " + CDeviceUtils::ConvertToString(data_bit) + " stop_bit: " + CDeviceUtils::ConvertToString(stop_bit));

Some good news is that we now have the convenient std::to_string(). We should be able to replace CDeviceUtils::ConvertToString(x) with std::to_string(x).c_str() in most cases. However,

• The formatting will not match in the case of double x
• Special case is needed for bool x if maintaining exact behavior
• We should ensure that there are no performance issues when used in the critical path of camera frame metadata generation (probably okay because formatted numbers usually fit in std::string's small-buffer optimization, meaning no allocation happens -- but something to be aware of)

In any case the solution is not quite trivial, and I don't want to add a deprecation warning for this (too many uses), so recording this issue for now.