Add support for multiple TLS certificates on a given app

Description of feature

It should be possible to add multiple TLS certificates to a single app. This is a large change, and we'd need to handle a few things:

• Updating report output to handle reporting on multiple certs
• Interactions with nginx-vhosts proxy plugin and k3s (on all ingress implementations, as well as the upcoming gateway api support)
• How to render the correct TLS certificate for a given domain
• Removing a specific TLS certificate, and how that would re-render the config for that app

Out of scope would be the proxy plugins that regenerate based on live docker containers.