Add mobile package name to js_xlr_pipeline

[cehan-Chloe]

xlr_compile already stamps a package's npm name into manifest.json via XLR_PACKAGE_NAME (added in the prior commit). This adds the same for iOS and Android, so a plugin's manifest can carry all three platform names in one place instead of just the npm one.

1. js_xlr_pipeline gets two new optional args, ios_package_name and android_package_name, alongside the existing package_name, and builds the package_names dict internally before calling xlr_compile — so callers keep passing flat string args
2. xlr_compile's npm_package_name string arg is replaced with one package_names dict, keyed by platform:

Any key can be omitted — only the platforms present get an env var (XLR_PACKAGE_NAME / XLR_IOS_PACKAGE_NAME / XLR_ANDROID_PACKAGE_NAME) set on the compile action, matching how a plugin without a mobile counterpart works today. An unrecognized key (e.g. a typo) fails the build immediately with a clear error, rather than being silently dropped.

Verified: built //plugins/reference-assets/react:react_xlr in the player-ui/player repo (via local_path_override) with --stamp, and confirmed the generated manifest.json contains matching react/ios/android entries with the same stamped version. Also rebuilt all 6 existing js_xlr_pipeline consumers in that repo to confirm no regression — the 5 without the new args still emit react-only manifests.

{
    "pluginName": "reference-assets-web-plugin",
    "capabilities": {
        "Assets": [
            "Assets.InputAsset",
            "Assets.TextAsset",
            "Assets.ActionAsset",
            "Assets.CollectionAsset",
            "Assets.ChoiceAsset"
        ],
        "Views": [
            "Views.InfoAsset"
        ]
    },
    "customPrimitives": [
        "Expression",
        "Asset",
        "Binding",
        "AssetWrapper",
        "Schema.DataType",
        "ExpressionHandler",
        "FormatType",
        "ValidatorFunction"
    ],
    "packages": {
        "react": {
            "name": "@player-ui/reference-assets-plugin-react",
            "version": "1.2.0-next.7"
        },
        "ios": {
            "name": "PlayerUIReferenceAssets",
            "version": "1.2.0-next.7"
        },
        "android": {
            "name": "com.intuit.playerui.plugins:reference-assets",
            "version": "1.2.0-next.7"
        }
    }
}