This PR introduces the /v1/search/fuzzy API endpoint, used for fuzzy
searching objects in Nomad. The fuzzy search endpoint routes requests
to the Nomad Server leader, which implements the Search.FuzzySearch RPC
method.

Requests to the fuzzy search API are based on the api.FuzzySearchRequest
object, e.g.

{
  "Text": "ed",
  "Context": "all"
}

Responses from the fuzzy search API are based on the api.FuzzySearchResponse
object, e.g.

{
  "Index": 27,
  "KnownLeader": true,
  "LastContact": 0,
  "Matches": {
    "tasks": [
      {
        "ID": "redis",
        "Scope": [
          "default",
          "example",
          "cache"
        ]
      }
    ],
    "evals": [],
    "deployment": [],
    "volumes": [],
    "scaling_policy": [],
    "images": [
      {
        "ID": "redis:3.2",
        "Scope": [
          "default",
          "example",
          "cache",
          "redis"
        ]
      }
    ]
  },
  "Truncations": {
    "volumes": false,
    "scaling_policy": ...