zulibot-action: Add commands-action.

[garg3133]

This PR adds the newly built Zulipbot commands-action to this repository.

Notes
For this action to work, the maintainers need to follow three additional steps:

• Get the Personal access token for Zulipbot's GitHub account (See the second paragraph of https://github.com/garg3133/zulipbot-action/tree/main/commands-action#create-a-github-account-for-the-bot).
• Add Zulipbot as a collaborator on this repository with admin access(if this isn't already the case).
• Save the Personal access token of Zulipbot as a secret on this repository, with the name BOT_ACCESS_TOKEN. (See https://github.com/garg3133/zulipbot-action/tree/main/commands-action#configure-bots-access-to-your-repository)

On a side note, I've set the current configuration of this action to match with the original Zulipbot configuration. So, do let me know if you need any changes in the configuration of this action. See the complete configuration of this action at https://github.com/garg3133/zulipbot-action/blob/main/commands-action/config/sample-config.yml.

This action covers only the @zulipbot claim/abandon/add/remove functionalities.

[garg3133]

The CI error seems to be unrelated to PR