Use npm's semver rules for plugin's nativescript key

tns plugin add の検証フローと、プラグインの package.json ファイルにある nativescript セクションから着手し、現在ランタイムのバージョンがどのように比較されているかを確認します。npm がドキュメント化している semver 範囲を使用し、完全一致、caret、tilde の値で提案された互換性の動作になるようにし、テストでサポート対象のランタイムバージョンと拒否されるランタイムバージョンの両方を検証します。

Problem with plugins verification with runtimes

Currently each NativeScript plugin must have nativescript key in it's package.json and define the minimum required version of each supported runtime. The structure is :

"name": "my-plugin",
"version": "1.0.0",
"nativescript": { 
    "platforms": {
        "ios": "1.5.0",
        "android": "1.5.0",
    }
}

When tns plugin add my-plugin is executed, CLI checks the values against current runtimes versions and informs the user if a plugin cannot be used with current version.
However CLI uses the specified version in the plugin as minimum required. So for example in case the project uses tns-android 1.6.0, 1.6.2 or even 2.0.0 for example, it can use my-plugin.
This makes it really hard to control the versions against which the plugin is tested and verified by the plugin author.

Suggested solution

Do not reinvent the wheel!
Use semver rules for the nativescript key in package.json, for example:

"name": "my-plugin",
"version": "1.0.0",
"nativescript": { 
    "platforms": {
        "ios": "^1.5.0",
        "android": "~1.5.0",
    }
}

This way in case the project targets android 1.5.2, the plugin can be installed, but in case it targets 1.6.0, the plugin will not be available. More information for the version ranges:
https://docs.npmjs.com/getting-started/semantic-versioning#semver-for-consumers

Breaking change

In case we implement this idea, all plugins, which currently has nativescript key inside their package.json, will not work, as the values: "1.5.0" will mean - can work with this version only.