Custom build target before deploy to netlify

[wiput1999]

Is your feature request related to a problem? Please describe.
I plan to use netlify-builder with Next.js. The problem is when building Next.js need additional step to deploy as static. It needs to run export command to build a production bundle and generate to static site. When I use nx affected:export as I've customized I found that I can't force buildTarget to export before deploy to Netlify.

Describe the solution you'd like
In src/deploy/index.ts#L29 I think if we can add custom builderOption like buildTarget which is default to build it will give me customization to change it to export which build and export static webpage for Next.js before deploying to Netlify.

If you allow me to PR so I can work on this and PR here. Maybe it doesn't relate to Angular directly so feel free to discuss. Thank you.