Implement Status checks

Description

As part of the MVC &8075 (closed) for editing branch rules, we need to be able to add/remove status checks.

Scope

To be updated by engineering

Implementation plan

• Create createExternalStatusCheck mutation
• Create editExternalStatusCheck mutation
• Create deleteExternalStatusCheck mutation

Mockups & behaviour

Figma

• Click "Add status check", display "Add status check" modal
• When "Edit" clicked, display "Update status check" modal
• When "Delete" icon button clicked, display delete modal (same like current)
  • title: Remove status check?
  • body: You are about to remove the {name} status check.
  • destructive primary: Remove status check
  • secondary: Cancel
• When change made and saved, display toast "Status check updated"
• When status check removed, display toast "Status check removed"

Description	Mockup
Default view
Add status check
Update status check
Delete status check