Inconsistencies across various configurations of HTTP listen endpoints

HTTP listener endpoints are used in three different places in the configuration:

1. When defining a publish target with method listen
2. When defining a publish target with method registry-v2
3. When defining a device type cwmp, in the server field

The addr field in the above cases is interpreted in different ways. For (1) and (3), it is read with url.Parse(), hence it requires a schema prefix as well as a host. For (2) it is passed directly to the http.Server.Addr so it accepts values like <host>:<port> or :port and does not accept schema.

Furthermore, although (1) requires a schema, it does not respect https and does not read the user-provided certificate fields so that it can spawn an https listener.

A common approach must be implemented; a listener should accept only :, in the same way that (2) is currently doing. User-provided certificate data should be respected to spawn TLS enabled https listeners.

Start by locating the three configuration paths for publish targets using listen and registry-v2, and the cwmp device type's server field; compare their url.Parse() and http.Server.Addr handling. Verify that all paths accept hostname:port values consistently and that the configured certificate data enables TLS listeners when provided.