Ability to add custom entries to Webpack and build manifest

[kevva]

Feature request

Is your feature request related to a problem? Please describe.

When using AMP together with amp-script, it'd be good if the script somehow could be transpiled. For example, if I would like to import preact and build some component I have to either introduce a second build step, or heavily modifiy the current Webpack config, if that's even possible.

I've tried to add custom entries, but they don't end up in the build manifest so I have no way of getting their path.

Describe the solution you'd like

The way I see it, there are two ways to go here. One way would be to magically find all the AMP script tags on the page that aren't remote and transpile them automatically during build. The other way would be to let users add custom entries in the Webpack config that would end up in the build manifest.