virtualhost.yaml with remap rules

[serrislew]

V2 of #12669 but including remap.yaml (#12997)

• Resolves to a single virtualhost entry
  • Remap rule logic remains the same. Order ranking still applies (i.e. rules defined first have priority)
  • Virtualhost remap rules have priority. If no remap rule matches or virtualhost is found, existing remap.yaml or .config is then considered
• Virtualhost domains support exact and wildcard (only single left-most "*") matching
• Supports traffic_ctl config reload of single virtualhost entry using reload directives
  • $ traffic_ctl config reload -D virtualhost.id=foo
  • Uses token model reload

[brbzull0]

I was talking with @serrislew about some parts of this PR, specially related to the interaction with the reload handler. I think #13110 is the plumbing that the id base reloading could benefit from.