Split destinations into name, ref, ref:to, ...

[freenerd]

We should do the same name-ref splitting as in https://github.com/Project-OSRM/osrm-backend/issues/2704 for destinations. Right now these are string concatenated but we've seen the need to separate these again (e.g. https://github.com/Project-OSRM/osrm-text-instructions/issues/51) Naming of fields and response is up for debate.

Example route that would be impacted

# OSM Tags
destination: "Chain Bridge;McLean"
destination:ref: "VA 123"

# OSRM Response Now
destinations: "VA 123: Chain Bridge, McLean"

# OSRM Response Fixed
destinations: {
  names: "Chain Bridge, McLean",
  refs: "VA 123"
}