feat: Allow customizing to-user-name/from-user-name

[pajlada]

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

Problem/Feature

This change allows a user to customize not only the ToUser ID & FromUserID, but also the accompanying Name fields that get sent through fake eventsub/websocket triggers.
Example usage: twitch-cli event trigger channel.ban --transport=websocket --to-user 11148817 --to-user-name pajlada

Description of Changes:

This change adds the two command line flags to the twitch-cli event trigger command:

• --to-user-name to accompany the already-existing --to-user flag
• --from-user-name to accompany the already-existing --from-user flag

Both new flags are optional, and not specifying them will mean no change in payloads.

Checklist

• My code follows the Contribution Guide
• I have self-reviewed the changes being requested
• I have made comments on pieces of code that may be difficult to understand for other editors
• I have updated the documentation (if applicable)