Update package format

[pschmitt]

There's a lot of legacy fields in the package.json files right now.
Most of the items in the root dir are ignored by zinit and are the result of an experiment that consisted in hosting zinit packages on npm.

Only ._resolved, .zsh-data.plugin-info[] and .zsh-data.zinit-ices[] are relevant.

Here's my first proposal draft:

{
    "author": "zdharma-continuum",
    "description": "Lorem ipsum bacon bacon",
    "name": "null",
    "message": "Thanks for trusting zdharma-continuum",
    "license": "MIT",
    "url": "https://github.com/zdharma-continuum/null",
    "version": "0.0.1",
    "requirements": [
        {
            "name": "Bin-Gem-Node",
            "type": "annex"
        },
        {
            "name": "cp",
            "type": "binary"
        }
    ],
    "profiles": {
        "default": {
            "message": "Installing default profile",
            "dl": "https://github.com/zdharma-continuum/null/null.tar.gz",
            "ices": {
                "null": true,
                "atclone": "echo 'installing'",
                "atpull": "echo 'updating'",
                "sbin": "null*",
                "make": "!",
                "run-atpull": true
            },
            "requirements": [
                {
                    "name": "test",
                    "type": "annex"
                }
            ]
        },
        "minimal": {
            "message": "Installing minimal profile",
            "plugin": "zdharma-continuum/null",
            "ices": {
                "atclone": "echo 'installing'",
                "atpull": "echo 'updating'",
                "run-atpull": "true"
            }
        }
    }
}

✨ Features:

• Profile-specific plugin definition (zinit will fetch different repos depending of the selected profile)
• Per-profile requirements
• Per-profile messages
• Clear distinction between regular and binary requirements (type prop)
• _resolved get a more appropriate name download