feat: differentiate live and cached toolchain resolution in dump-state

[Kha]

$ elan dump-state
    "default": {
      "unresolved": {
        "Remote": {
          "origin": "leanprover/lean4",
          "release": "stable",
          "from_channel": "stable"
        }
      },
      "resolved": {
        "live": {
          "Ok": "leanprover/lean4:v4.14.0"
        },
        "cached": {
          "Ok": "leanprover/lean4:v4.9.0"
        }
      }
    },
    "active_override": null,
    "resolved_active": {
      "live": {
        "Ok": "leanprover/lean4:v4.14.0"
      },
      "cached": {
        "Ok": "leanprover/lean4:v4.9.0"
      }
    }

$ elan dump-state --no-net
    "default": {
      "unresolved": {
        "Remote": {
          "origin": "leanprover/lean4",
          "release": "stable",
          "from_channel": "stable"
        }
      },
      "resolved": {
        "live": {
          "Err": "Cannot fetch latest release tag under `--no-net`"
        },
        "cached": {
          "Ok": "leanprover/lean4:v4.9.0"
        }
      }
    },
    "active_override": null,
    "resolved_active": {
      "live": {
        "Err": "Cannot fetch latest release tag under `--no-net`"
      },
      "cached": {
        "Ok": "leanprover/lean4:v4.9.0"
      }
    }