Add layer_arn function.

[fujiwara]

resolve lambda layer arn.

Resolve Lambda layer ARN

The layer_arn template/Jsonnet function resolves the Lambda layer ARN.

{
  "Layers": [
    "{{ layer_arn `my-layer` `latest` }}"
  ]
}

local layer_arn = std.native('layer_arn');
{
  Layers: [
    layer_arn('my-layer', 'latest'),
  ],
}

The layer_arn function takes two string arguments: LayerName and Version.

• LayerName is the name of the Lambda layer.
• Version is the version of the Lambda layer. If Version is empty or latest, the latest version is used. Otherwise, the specified version is used.