This Pull Request includes a new feature to send notifications on Slack channels when an alert is triggered.

Deployment Considerations

It is necessary to configure a Slack App for Prebunking At Scale alerts system to allow admin users to include it on their workspaces and receive notifications on the Slack Channels that they select. To create an app, follow the next steps:

1. Visit the Slack api website and Sign In: https://api.slack.com/apps
2. Create a new App and select "from scratch". The form will ask for a name to identify the App (this name will be shown to the users when installing the app on their workspaces) & a Slack workspace to develop the app in, it can be any workspace since the App will be configured as publicly distributed later. Submit the form.
   
3. The website will redirect to the App settings page, here it'll be necessary to copy the Client ID and Client Secret values since these are required to configure the programmatic access by defining them as environment variables as it is explained later.
   
4. Optional. Configure the Display Information on the same App settings page. This information will be shown when the app is installed on the desired workspaces, so it will be ideal to help users identify the application as part of EFCSN PAS system.
   
5. Enter on Incoming Webhooks option menu and activate it.
   
6. Enter on OAuth & Permissions option menu. On Redirect URLs section, add the backend's base API URL and save.
   
7. Enter on Manage Distribution option menu. On Share Your App with Other Workspaces section, mark the "I’ve reviewed and removed any hard-coded information." and press Activate public distribution button.
   
8. Enter on OAuth & Permissions. On Scopes section, add the chat:write on bot token's section. Here it will ask to add a reason why the app is requesting these permissions but they are not required to proceed.
   
9. Finally, the app is configured correctly to use it on the core api server. Add the following environment variables:

SLACK_CLIENT_ID=<CLIENT_ID_FROM_STEP_3>
SLACK_CLIENT_SECRET=<CLIENT_SECRET_FROM_STEP_3>
# this url is a new endpoint defined on the core api to complete the authorization step on the Slack workspace
SLACK_REDIRECT_URI=<API_BASE_URL>/api/integrations/slack/oauth/callback