Added several new API endpoints and webhooks

Added

• New Assignee APIs:

  • POST /v2/tasks/items/{taskId}/assignees
  • DELETE /v2/tasks/items/{taskId}/assignees/{userId}
  • GET /v2/tasks/items/{taskId}/assignees

• New Comment APIs:

  • GET /v2/tasks/items/{taskId}/comments
  • DELETE /v2/tasks/items/{taskId}/comments/{commentId}
  • POST /v2/tasks/items/{taskId}/comments

• New Tasks APIs:

  • GET /v2/tasks/items/{taskId}
  • POST /v2/tasks/items
  • GET /v2/tasks/items
  • PATCH /v2/tasks/items/{taskId}
  • DELETE /v2/tasks/items/{taskId}

• New Collaborator APIs:

  • DELETE /v2/tasks/items/{taskId}/collaborators/{userId}
  • GET /v2/tasks/items/{taskId}/collaborators
  • POST /v2/tasks/items/{taskId}/collaborators

• New Comment webhook event:

  • task.comment_updated

• New Collaborator webhook event:

  • task.collaborator_updated
  • task.assignee_updated

• New Tasks webhook event:

  • task.deleted
  • task.updated
  • task.completed
  • task.created
  • task.reopened