[receiver/mongodbatlas] Retrieve Alerts Data Through Firewall

[schmikei]

Is your feature request related to a problem? Please describe.

The MongoDB Atlas receiver currently can collect alerts via webhooks. This doesn't work for all customers as they may not be able to open a port in the firewall to accept incoming alerts.

We should add an alternative that allows us to scrape the API for Alerts so that this user case is accomplished.

Describe the solution you'd like

I'd like to propose that we introduce a new mode parameter for the alerts config as to dictate whether to listen or retrieve logs from the API.

receivers:
  mongodbatlas:
    alerts:
      enabled: true
      # new parameters
      mode: poll # one of poll or listen
      projects:
      - name: project-1
        exclude_clusters: [internal_cluster]
        include_clusters: []

Describe alternatives you've considered

Deliberated between adding a new config or mode only parameters and feel like this would be my preference happy to hear other thoughts/concerns though!

Additional context

No response

[schmikei]

I will be taking a look at addressing this

[github-actions]

Pinging code owners: @zenmoto. See Adding Labels via Comments if you do not have permissions to add labels yourself.