[Type 1] Add support for API method Update a Webhook  #1135

Description

Tableau REST API provides a method to modify the properties of an existing webhook which is not currently exposed through TSC:
https://help.tableau.com/current/api/rest_api/en-us/REST/rest_api_ref.htm#update_webhook

This method is useful for easily re-enabling webhooks when they get disabled after four failed re-tries.

Consider surfacing additional webhook attributes like isEnabled and statusChangeReason as a part of webhook_item model to better support webhook management.

As per note in Tableau REST API documentation review TSC code to use the event attribute of the webhook to specify the triggering API event for the webhook as the webhook-source element is being deprecated in future versions of Tableau webhooks.