When GetWebhooks returns webhooks, headers and customFields are masked
with ***REDACTED*** for security. However, when the frontend toggled
a webhook's enabled state, it sent back the redacted values, which
overwrote the actual header values (like Authorization tokens).
This broke webhooks after disabling and re-enabling them, as the auth
headers were replaced with "***REDACTED***".
Now UpdateWebhook detects redacted values and preserves the original
headers/customFields from the existing webhook.
Related to #938
rcourtman
7f8c9e37b1