Setting application parameters via CLI

[cz4rny]

Is your feature request related to a problem? Please describe.
To achieve deployment reproducibility, reverting to the last working commit in particular, I'd like to be able to pass ArgoCD app parameters, or by any other means be able to pass the ${CI_COMMIT_SHA} from a GitLab pipeline.

Describe the solution you'd like
Either:

• Get ArgoCD cli to be able to argocd app set -p parameter=value for a Plugin type app, as it currently allows only ApplicationSourceTypeHelm even though the demo application.yaml also shows values for plugins.
• Provide a mechanism to pass environment variables other than the AVP_ ones.

Describe alternatives you've considered

• argocd app set
• Setting custom env variables via CLI

Additional context
As per AVP usage instructions, we're modifying the Application manifests from helm to plugin.