feat(snooze): request longer snooze

[whitdog47]

This pull request introduces the ability to request a longer snooze period for signals within the Slack integration.

Key changes:

• Database Migration:
  • Adds snooze_extension_oncall_service_id to the project table to associate an on-call service with snooze extension requests.
  • Includes corresponding upgrade and downgrade Alembic migrations.
• Slack Interactive Elements:
  • Adds a checkbox (extension_request_checkbox) in the snooze creation modal to allow users to request a longer snooze.
  • Updates the snooze submission handler (handle_snooze_submission_event) to process this request.
• Snooze Message Enhancement:
  • Modifies the snooze notification message (post_snooze_message) to indicate if an extension was requested and notifies the on-call user.
  • Adds a function get_user_id_from_oncall_service to get the slack user id from the oncall service.
• Project Model Update:
  • Adds snooze_extension_oncall_service relationship to the Project model.
  • Adds snooze_extension_oncall_service_id to ProjectBase, ProjectCreate, and ProjectUpdate models.
• Vue UI Changes:
  • Adds a ServiceSelect component to the NewEditSheet.vue to allow project admins to select the oncall service for snooze extensions.
  • Updates the project store to handle the new field.
• Testing:
  • Adds comprehensive unit tests for the new snooze functionality, including handling of MFA challenges and on-call service notifications.

Benefits:

• Provides users with the flexibility to request longer snooze durations when necessary.
• Ensures that on-call personnel are notified when a snooze extension is requested.
• Improves the overall signal management workflow within Slack.

Screen shots: