* whisper : improve whisper-cli executable path detection in model download shell scripts
If whisper-cli is found on the path, do not suggest invoking from build directory. This improves flexibility and usability for distribution and packaging scenarios.
* whisper : enhance Windows model download batch script to have comparable functionality and behaviour as shell scripts
* Download models to the current directory if the script is executed from the \bin\ directory (for future distribution scenarios where the script is in the \bin\ subdirectory of a Windows build)
* Add model_path command line argument
* If whisper-cli is found on the path, do not suggest invoking from build directory
* whisper : resolve compiler warning by removing duplicate definition of NOMINMAX in whisper-cli code
