Send alerts to Google Chat

[aportosa]

Is your feature request related to a problem? Please describe.
Elementary currently supports sending alerts via Slack and Microsoft Teams, but lacks support for Google Chat, which is a popular communication platform for many teams. This limits the observability options for data teams using Google Chat as their primary communication channel.

Describe the solution you'd like
Add native support for sending Elementary data observability alerts to Google Chat using webhooks. This should include:

• Support for sending all existing alert types (Elementary tests, DBT tests, model errors, etc.)
• Configurable webhook integration via CLI
• Ability to mention users in alerts
• Consistent formatting with existing Elementary integrations

Describe alternatives you've considered

None are applicable here.

• I cannot switch from Google Chat to Slack or Teams.
• I cannot use any third-party integration like Zapier to build complex alert forwarding system to achieve worse result than a native integration.

Additional context

• Webhook-based integration minimizes complexity
• Follows existing Elementary integration patterns (https://github.com/elementary-data/elementary/tree/master/elementary/monitor/data_monitoring/alerts/integrations)
• Provides flexibility for teams using Google Chat

Would you be willing to contribute this feature?
Yes, I have already developed an initial implementation of the Google Chat client and I am prepared to contribute the full integration.