jspm build: Make rollup configuration optional

[guybedford]

A standard rollup configuration shouldn't be provided by default without needing an explicit configuration file for simple build cases.

[JayaKrishnaNamburu]

It's possible with the following commands without passing config.
https://codesandbox.io/p/devbox/jspm-build-n65wdt?file=%2F.codesandbox%2Ftasks.json%3A19%2C1

jspm build index.js --output build.js

[guybedford]

Great, thanks for verifying. Is there anything else we need to do here then?

[JayaKrishnaNamburu]

Maybe we can start supporting some of the config like inlineDynamicImports etc.
Eg: We can just use the command instead of passing rollup-config for vs-code extension.

Instead of passing config like this

jspm build -r @babel/helper-module-transforms=@babel/helper-module-transforms@7.21.2 --config rollup-config.mjs

it can become this

jspm build -r @babel/helper-module-transforms=@babel/helper-module-transforms@7.21.2 --inlineDynamicImports

But apart from that, the basic building and stuff are good.

[guybedford]

Yes, like wrapping the Rollup CLI itself.