[v2.x] Add BMC Let's Encrypt support for automated SSL cert generation

[srcshelton]

Is your feature request related to a problem? Please describe.
As an end-user, I would like my TP2 BMC to use CA-signed rather than self-signed certificates without the need to manually replace certificates upon expiry.

Describe the solution you'd like
Add a WebUI panel to collect the necessary information & automation in order to use the Let's Encrypt API to generate a signed SSL certificate, and replace it before expiry (as well as invalidate and replace any certs which must be revoked if ever required).

Describe alternatives you've considered
dehydrated provides a pure-bash ACME client if space is at a premium and the default client is too large.

Additional context
It would be great, if implemented, to support DNS-based authentication (at least when using certain common services, such as Cloudflare).

[soxrok2212]

An alternative solution is to run everything behind a proxy and have all your certificates there instead. Then you only need to have certbot/letsencrypt running in one place.

[tantalic]

The acmed project seems like it would be a good fit to integrate in for this functionality https://github.com/breard-r/acmed

[gclawes]

+1 to this.

A great homelab use case is running SmallStep ACME CA: https://smallstep.com/blog/private-acme-server/