Description of change

• feat: add --systemPromptFile flag to the chat command
• feat: add --promptFile flag to the chat command
• feat: add --batchSize flag to the chat command

Based on #145 by @stewartoallen, adapted for the beta branch.

This is a new PR to merge to the beta branch instead of the master branch (supersedes the #147 PR)

Pull-Request Checklist

• Code is up-to-date with the master branch
• npm run format to apply eslint formatting
• npm run test passes with this change
• This pull request links relevant issues as Fixes #0000
• There are new or updated unit tests validating the change
• Documentation has been updated to reflect this change
• The new commits and pull request title follow conventions explained in pull request guidelines (PRs that do not follow this convention will not be merged)