fix: environment and feature names in pixi info --json

[baszalmstra]

Changes the output of project info --json to output proper environment names:

before:

{
      "name": {
        "Named": "pl017"
      },
      "features": [
        {
          "Named": "pl017"
        },
        {
          "Named": "py310"
        },
        {
          "Named": "test"
        },
        "Default"
      ],

after:

{
      "name": "pl017",
      "features": [
        "pl017",
        "py310",
        "test",
        "default"
      ],

Im also wondering if the "default" feature should be include in the above list ..

[ruben-arts]

Works for me!