implement list commands

[bacongobbler]

relies on #121

This is a rough implementation of hippo app list, hippo channel list, hippo env list, etc. It lists ALL objects of each resource. Eventually this will only be an endpoint available to administrators once deislabs/hippo#575 is implemented, but until then it's a handy introspection tool for developers/administrators.

note that several commands do not work due to fermyon/hippo-openapi#6. Once that's fixed, commands like hippo channel list and hippo app list should work.

[bacongobbler]

issues should be resolved once #122 is merged

[bacongobbler]

output:

><> ./target/debug/hippo app list
[
  {
    "id": "57a4eaba-2b4b-41b6-b0ca-772c108e4868",
    "name": "carstar",
    "storageId": "carstar",
    "channels": [
      {
        "id": "c8f94b04-0ecb-4d3a-a583-79ddde9e051f",
        "appId": "57a4eaba-2b4b-41b6-b0ca-772c108e4868",
        "name": "latest",
        "domain": "latest.carstar.hippo.localdomain",
        "revisionSelectionStrategy": "UseRangeRule",
        "rangeRule": "*",
        "environmentVariables": [
          {
            "id": "7b57c6c8-66fb-46b0-98d6-c1573778844f",
            "channelId": "c8f94b04-0ecb-4d3a-a583-79ddde9e051f",
            "key": "FOO",
            "value": "bar"
          }
        ]
      }
    ],
    "revisions": []
  },
  {
    "id": "5971e71d-dea2-45a2-b23d-0937b3031b6d",
    "name": "docs",
    "storageId": "spin-docs",
    ...

This now allows someone to pipe this to jq:

><> ./target/debug/hippo app list | jq '.[0].id'
"57a4eaba-2b4b-41b6-b0ca-772c108e4868"