Update the Angular CLI and Angular framework packages to latest `@next`
versions. Also, update the app to look more closely to how a newly
generated app with the latest CLI would look like.
PR Close#36145
This shouldn't change anything. But it's interesting that we used to have this import
that seemed bogus, but there were no compilation or rutime errors.
All the docs related files (docs-app, doc-gen, content, etc)
are now to be found inside the `/aio` folder.
The related gulp tasks have been moved from the top level
gulp file to a new one inside the `/aio` folder.
The structure of the `/aio` folder now looks like:
```
/aio/
build/ # gulp tasks
content/ #MARKDOWN FILES for devguides, cheatsheet, etc
devguides/
cheatsheets/
transforms/ #dgeni packages, templates, etc
src/
app/
assets/
content/ #HTML + JSON build artifacts produced by dgeni from /aio/content.
#This dir is .gitignored-ed
e2e/ #protractor tests for the doc viewer app
node_modules/ #dependencies for both the doc viewer builds and the dgeni stuff
#This dir is .gitignored-ed
gulpfile.js #Tasks for generating docs and building & deploying the doc viewer
```
Closes#14361