--useHttps with --cert does not use the specified certificate

Running `func start --useHttps --cert "path to certificate"` results in the message _Generating a self signed certificate using openssl_, which is not expected.

Example at https://github.com/pellebjerkestrand/azure-functions-core-tools-cert-bug

Reproduce `func start --useHttps --cert "path to certificate"` and inspect the CLI path handling these options. Use the linked certificate example to compare the requested certificate with the reported self-signed generation. Done means the specified certificate is used and the generation message is not shown.

Written by the indexing model from the issue text.