feat: get pod json

[jojje]

Add json format option to get pod command

Always produces a list output, even if a specific pod ID is provided. Stays semantically aligned with the text table view which also shows collection outputs regardless of matched pod(s).

Addresses #148 (comment) but not the entire issue #148 which seems to ask for json output for all commands.

How I tested it

• Unit test
• Manual integration test against backend api

Example output

runpodctl get pod --json

output:

[
  {
    "Id": "wwp6rwl5wucng8",
    "ContainerDiskInGb": 20,
    "CostPerHr": 0.24,
    "DesiredStatus": "RUNNING",
    "DataCenterId": "",
    "DockerArgs": "",
    "Env": [
      "PUBLIC_KEY=ssh..."
    ],
    "GpuCount": 1,
    "ImageName": "runpod/pytorch:2.4.0-py3.11-cuda12.4.1-devel-ubuntu22.04",
    "MemoryInGb": 31,
    "Name": "young_purple_kangaroo",
    "PodType": "RESERVED",
    "Ports": "8888/http,22/tcp",
    "VcpuCount": 6,
    "VolumeInGb": 20,
    "VolumeMountPath": "/workspace",
    "Machine": {
      "GpuDisplayName": "RTX 2000 Ada",
      "Location": "RO"
    },
    "Runtime": {
      "Ports": [
        {
          "Ip": "100.65.24.183",
          "IsIpPublic": false,
          "PrivatePort": 19123,
          "PublicPort": 60755,
          "PortType": "http"
        },
        {
          "Ip": "213.173.102.150",
          "IsIpPublic": true,
          "PrivatePort": 22,
          "PublicPort": 31696,
          "PortType": "tcp"
        },
        {
          "Ip": "100.65.24.183",
          "IsIpPublic": false,
          "PrivatePort": 8888,
          "PublicPort": 60754,
          "PortType": "http"
        }
      ]
    }
  }
]