feat(admin-ui): Implement security measures for webhook

[syntrydy]

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Description

Currently the webhook feature doesn't have any security measures implemented. The following should be done:

• Perform URL validation.
• Ensure URL starts with "https://", disallow "file://" and other non-HTTPS schemes.
• Block typical local IPs: 127.0.x, 192.168.x, 172.x.
• Prohibit "localhost" and "http://"
• Require a specific response header for POST requests, unique to the customer.

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