This commit moves the build-related scripts
(`build-ivy-npm-packages.js`, `build-packages-dist.js` and
`package-builder.js`) to a dedicated directory to keep the `scripts/`
directory cleaner.
It also moves the logic for building the `zone.js` package to a separate
script, `zone-js-builder.js`, to make it re-usable. A subsequent commit
will use it to build the `zone.js` package when building the Ivy Angular
packages as well.
PR Close#35780
* Remove now unnecessary portions of build.
* Add a compilePackageES5 method to build ES5 from sources
* Rework all package.json and rollup config files to new format
* Remove "extends" from tsconfig-build.json files and fixup compilation roots
PR Close#18541
Previous to 2.x there were some source maps distrubted, but they didn't go
all the way back to the TypeScript sources and they weren't available for
all JavaScript distrubted to NPM.
With this change source maps will be available for FESM distributions as
well as UMD and will go all the way back to TypeScript sources.
Fixes#15184