Support pluggable communication platforms

[pkosiec]

Overview

Currently, there are multiple feature requests for different chat platforms:

• Telegram Support #50
• Add support for RocketChat #56
• email notification  #311
• Implement feature to ingrate with Zoom Messenger  #535
• Support for Google Chat #554
• Hope to be able to support WeCom #1114
• Add Support for Webex Teams Integration #470
• [FR] Support for Matrix notifications #503

Unfortunately, we cannot support all the solutions because of the too big maintenance efforts. However, what we can do, is to abstract the communication platforms and make them extensible – just how we did with executors and sources.

Acceptance Criteria

• Extract current communication platforms to plugins
  • Define gRPC API contract
  • Update configuration (communications property)
  • Release the comm platforms as separate plugins
  • Ensure the plugins are properly downloaded during Botkube startup
• Create botkube-plugins-contrib repo (or similar), to host community-maintained comm platform plugins
• Extract some of the current platforms to the botkube-plugins-contrib - e.g. elasticsearch, Teams?
• Migrate some of the comm platform related issues to the botkube-plugins-contrib repo
• Make sure documentation is up-to-date, create one if needed
• Add test coverage for happy-path (unit or e2e test)
• Record raw demo video for the user-facing changes

Reason

Ensure users can use Botkube with their own communication platforms, even though we can't support them officially.