Fn::StringAsset doesn't handle expressions

[cnunciato]

What happened?

In other languages, I can declare a StringAsset using, say, an output from another resource:

const app = new azure_native.web.WebApp("app", {
    // ...
});

const configFile = new azure_native.storage.Blob("config.json", {
    source: app.defaultHostName
        .apply(hostname => new pulumi.asset.StringAsset(JSON.stringify({ 
            apiEndpoint: `https://${hostname}/api` 
        }))),
    contentType: "application/json",
    // ...
});

When I try this with YAML, though:

configFile:
    Fn::StringAsset: '{ "apiEndpoint": https://${app.defaultHostName}/api }'

I get an error:

error: could not load yaml program: failed to load the template: Pulumi.yaml:34,22-75: 
    The argument to Fn::StringAsset must be a string literal; 

Ideally, YAML would support interpolation like this as well.

Steps to reproduce

See above.

Expected Behavior

The StringAsset is created in the usual way.

Actual Behavior

See above.

Output of pulumi about

CLI
Version      3.40.1
Go Version   go1.19.1
Go Compiler  gc

Host
OS       darwin
Version  12.5.1
Arch     x86_64

Additional context

No response

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