There are no means of setting the esbuild format to ESM

[giseburt]

When building a TypeScript App to bundle with the Bundler, things like top-level await need bundled differently.

esbuild provides this control via the --format=esm flag: https://esbuild.github.io/api/#format

There's not even a clean escape hatch that doesn't completely blow away the build tasks. (There's no means of adding to a task command, AFAICT, and I'm not sure I'd really want to do that anyway, as it seems terribly fragile.)

This is simple to add, and I'll have a PR for it ready soon.

[mrgrain]

Do we also want to add escape hatches for other unsupported / unknown options in esbuild? Similar to how the AWS CDK NodejsFunction has the esbuildargs?

@giseburt Yes! That would be awesome!