[native_assets_cli] Fallback asset types supportedAssetTypes

[dcharkes]

Hook authors might want to use a certain asset type if available, and another one if the first one is not available.

• CodeAsset, and if not available WasmAsset (Compilation of native code to WASM #156).
• JarAsset, and if not available, CodeAsset (for libraries that are available as Jars and native).

For these it could be useful to have an input.config.supportedAssetTypes which signals with which input.config.buildAssetTypes the hook will be invoked besides the current invocation.

Edit: The SDKs could invoke the hooks for all asset types and based on asset-ids decide for one asset over another. However, the Dart code might make the JarAsset available under a different asset ID than the CodeAsset. (Or a JarAsset might not even have an asset ID.)

[mosuem]

I think the SDKs should make that decision - the hooks should just build assets based on what the SDK is asking for.