build: publish tree of files rather than FESMs (#18541)

* 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

packages/upgrade/static/rollup.config.js

@@ -7,18 +7,19 @@
  */
 
 import resolve from 'rollup-plugin-node-resolve';
+import sourcemaps from 'rollup-plugin-sourcemaps';
 
 const globals = {
   '@angular/core': 'ng.core'
 };
 
 export default {
-  entry: '../../../dist/packages-dist/upgrade/@angular/upgrade/static.es5.js',
+  entry: '../../../dist/packages-dist/upgrade/esm5/static/index.js',
   dest: '../../../dist/packages-dist/upgrade/bundles/upgrade-static.umd.js',
   format: 'umd',
   exports: 'named',
   moduleName: 'ng.upgrade.static',
-  plugins: [resolve()],
+  plugins: [resolve(), sourcemaps()],
   external: Object.keys(globals),
   globals: globals
 };