feat: revamped make-everyvoice-env script
- make ./make-everyvoice-env the documented default way to call it, instead of
bash make-everyvoice-env
- proper command-line argument parsing
- command line options: --cuda CUDA_VERSION and --cpu
- for @SamuelLarkin support -p/--path PATH like conda does, and use -n/--name
ENVIRONMENT instead of my positional argument for the env name (default
would remain --name EveryVoice as now).
