Support for Bring your own certificates (.pfx)

[Marty-Me]

The current Kafka Trigger implementation requires the file names for the key and certificate file in .pem format.
This requires developers to either package the .pem files with the .zip, or store the files on the file-system somehow.

I propose to add support for certificates which are already installed through the "Bring your own certificates (.pfx)"-feature of App Service Plan hosted Function Apps.

https://learn.microsoft.com/en-us/azure/app-service/configure-ssl-certificate?tabs=apex#upload-certificate-to-app-service