Dispatcher Proxy Support

[whitej6]

Environment

• Nautobot version: latest
• nautobot-plugin-chatops version: latest

Proposed Functionality

Add configuration for each dispatcher to support http proxy (if upstream sdk supports).

Use Case

Slack socket mode without outbound internet access.

[smk4664]

This is more documentation than anything else. Under the hood, Requests and SlackAPIClient both honnor the HTTP_PROXY/HTTPS_PROXY Environment Variables.

[whitej6]

May be worth implementing separately since the env var applies globally for those libs