Add support for Windows

[brainwavecoder9]

What this does

Windows uses COM ports not what is expected for Linux/Mac. This commit adds support for Windows OS. It does this by:

• checking to see if OS is Windows, or other
• if Windows, use a new process
• if other, use existing process

There is a dependency (pyserial) but it is already in the environment so no changes there. Once the port is identified it can be added to the .yaml the same as it is today. Although it will be referenced differently (e.g., COM7 vs. /dev/ttyACM) the rest of the functionality still works.

How it was tested

Successful in Windows environment, and theoretically won't affect others, but does need to be confirmed before merge.

How to checkout & try? (for the reviewer)

No change to existing process. To use, simply execute the existing script, e.g., python lerobot/scripts/find_motors_bus_port.py