net/haproxy: Backend Server unable to use IPV6 Address. Syntax Checking fails.

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Describe the bug
Setting a backend server's ip address to a valid IPV6 address results in a message like
'server $SERVER' : invalid character '$CHAR' in port number '$HEXTET' in '$IPV6_ADDRESS'

Adding brackets is impossible, otherwise the "Edit Server" dialog returns
Please specify a valid servername or IP address.

To Reproduce
Steps to reproduce the behavior:

1. Go to 'Services -> HAProxy -> Settings'
2. Click on 'Real Servers'
3. Click on 'Add'
4. Enter IPv6 address in 'Static Server -> IP or FQDN'

Expected behavior
Expected IPV6 address to be accepted and syntax test to pass.

Additional context
HAProxy is being used to load balance multiple servers not located on the OPNSense box.
I see some validation on line 262 here, but it doesn't look like that's where the actual validation and parsing is taking place.

After sleeping on it, it seems the code (wherever it is) reads the string from right to left, and treats the first colon as the delineation between the server address and port number.

Environment
OPNsense 21.7.7-amd64
Intel(R) Xeon(R) CPU E31225 @ 3.10GHz (4 cores)