Important notices
Before you add a new report, we ask you kindly to acknowledge the following:

• I have read the contributing guide lines at https://github.com/opnsense/plugins/blob/master/CONTRIBUTING.md
• I have searched the existing issues, open and closed, and I'm convinced that mine is new.
• When the request is meant for an existing plugin, I've added its name to the title.

Is your feature request related to a problem? Please describe.

My netbird install is hosted behind a opnsense firewall. I want said opnsense firewall to report correct "Public IP Address" to netbird. Firewall has a static ip so this should be straight forward once the option is exposed in the web interface.

Describe the solution you'd like

I would like to see the "--external-ip-map" option exposed in the opnsense web interface

See netbird docs for more details about "--external-ip-map" -> https://docs.netbird.io/get-started/cli#flags

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
Add any other context or screenshots about the feature request here.