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/examples/tsconfig-build.json

@@ -1,27 +1,19 @@
 {
+  "extends": "../tsconfig-build.json",
+
   "compilerOptions": {
-    "baseUrl": ".",
-    "declaration": true,
-    "stripInternal": true,
-    "experimentalDecorators": true,
-    "noImplicitAny": true,
-    "strictNullChecks": true,
-    "emitDecoratorMetadata": true,
     "module": "commonjs",
-    "moduleResolution": "node",
-    "outDir": "../../dist/examples",
+    "emitDecoratorMetadata": true,
+    "baseUrl": ".",
+    "rootDir": ".",
     "paths": {
       "@angular/*": ["../../dist/packages-dist/*"],
       "rxjs/*": ["../../node_modules/rxjs/*"]
     },
-    "rootDir": ".",
-    "sourceMap": true,
-    "inlineSources": true,
-    "target": "es5",
-    "lib": ["es2015", "dom"],
-    "skipLibCheck": true,
+    "outDir": "../../dist/examples",
     "types": ["jasmine", "node", "angularjs", "systemjs"]
   },
+
   "include": [
     "./**/*.ts",
     "../../node_modules/zone.js/dist/zone.js.d.ts",