Add BS 34-1A precision voltage source

[OljaKhor]

This PR provides initial support for the Stahl Electronics BS 34-1A precision multichannel voltage source. It uses a basic time-based voltage-setting approach with time.sleep(t) in a background thread, since the device unfortunately lacks an internal clock and buffering. The implementation also follows a modular structure similar to NI_DAQmx, defined via capabilities.json and subclassing.

The current implementation has been tested with our BS 34-1A unit and performs reliably in both manual and buffered modes. (An emulator is also included for manual testing without physical hardware.)

Further documentation and connection table example can be found in the readme.md

Suggestions and improvements are very welcome!