os-caddy: Manually trigger certificate renewal

[Stitch10925]

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

• [v] I have read the contributing guide lines at https://github.com/opnsense/plugins/blob/master/CONTRIBUTING.md
• [v] I have searched the existing issues, open and closed, and I'm convinced that mine is new.
• [v] 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.
Namecheap API is bound to an IP address, since my IP address is dynamic Caddy cannot update my IP anymore in Namecheap which also causes certificate validation to fail.

Describe the solution you'd like
I would like to be able to manually trigger a certificate update so that, once my IP has been set up correctly and stale TXT records have been removed, so I don't have to wait for the next time acme runs.

[Monviech]

This is how caddy works:

https://caddyserver.com/docs/automatic-https#errors

Just restart the service using the service buttons and it should start this same pattern immediately from the beginning.