Provide option to run locally installed bids-validator

[gabridele]

Closes #376

Changes proposed in this pull request

• when user provides --local-validator argument to the cubids validate command, it runs the locally installed bids-validator. For use cases where HPCs don't have internet access
• added argument to parsing function
• updated calling of validate function by adding new argument
• build_validator_call has now if statement to accommodate choice of local validator

Documentation that should be reviewed

• Section regarding installation and prerequisited
• Adding sections/'boxes' for internetless use cases (might only apply to cubids validate so far)

[tien-tong]

add docstrings to the functions you're editing, if they don't have it already, or only had partial infor

[tien-tong]

please fix lint issues, you can run black on the script and push your changes until it passes lint test

[gabridele]

Done!

[tien-tong]

@gabridele can you also add instruction on how to download the new schema validation via deno to the documentation?

[gabridele]

@tientong98 will do, as soon as I'm done with another issue