Allow for Local LetsEncrypt - Boulder private Certificate Authority

Describe the solution you'd like
Allow the LetsEncrypt to use local CA provider like the self hosted version of LetsEncrypt - Boulder (https://github.com/letsencrypt/boulder)

and the Project LabCA that uses Boulder - https://lab-ca.net/ Github: https://github.com/hakwerk/labca

Describe alternatives you've considered

to be able to uses the Certificate from Labca or LetsEncrypt - Boulder you need to request the cert with certbot and then add the 90day cert as a custom cert in nginx proxy manger, where NPM is using certbot already to request the cert.

all that would needed to be add is to allow the use of referencing the trusted-root-certificate ACMEDirectoryResourceURI

could also work with issue: Support for Manual DNS-01 Challenge (Custom _acme-challenge TXT Record)

Start by tracing the existing certbot integration in the nginx-proxy-manager repository. Read the Boulder and LabCA links and investigate how ACMEDirectoryResourceURI could reference a trusted local CA, including the relationship to the linked manual DNS-01 issue. Done would mean a defined, tested way to request and use certificates from a local Boulder-compatible CA.