manager: datamodel: lower verbosity for network/listen configuration

Note: the examples don't reflect later changes in this MR.

Simplified configuration of network/listen.

• list of values can be used for ip-address, interface or unix-socket (e.g. ip-address: [127.0.0.1, ::1])
• @port syntax can be used with ip-address and interface (e.g. ::1@5353, eth0@5353)
• advanced validation

Examples

network:
  listen:
    - unix-socket: /tmp/kresd-socket
    - ip-address: 127.0.0.1
      port: 5353
    - ip-address: ["127.0.0.1@5353", "::1@5353"]
      kind: dot
    - ip-address: ["127.0.0.1", "::1"]
      kind: dot
    - interface: ["lo", "eth0"]
      port: 5555
      kind: doh2
    - interface: ["lo@5555", "eth0@5656"]
      kind: doh2

If port number is specified by port option and @port, the config is invalid.

network:
  # this is all invalid
  listen:
    - ip-address: 127.0.0.1@5353
      port: 5555
    - ip-address: ["127.0.0.1@5353", "::1"] # invalid, @port must be specified for all values or for none
      kind: dot

Closes #703 (closed)