feat: Bump example project to Angular 8

[wtho]

I did most adjustments to be in sync with the default Angular CLI Boilerplate. I know many Angular projects will still differ from this, but I feel like it is the default starting point in the community. Open to discussion regarding this.

Changes in example project:

• Removed the whole e2e section in angular.json, as it looks quite different in current generated projects, but updating also the e2e folder seemed out of scope.
  Question: Should we remove the e2e source folder as well? Or keep everything also in angular.json in sync to the boilerplate of angular 8?
• I am not sure about the dependencies. Angular projects now lock the versions inside package.json using ~x.x.x.
  Question: Should we keep all versions locked in the example project as well?
• Removed core-js from peerDependencies, it is not a dependency of Angular projects anymore, and made it a dependency of jest-preset-angular, as we need it for testing. See Angular no longer directly depends on core-js - should not be a peerDependency #266 for further discussion.
• Replaced HttpModule with HttpClientModule (HttpModule was dropped completely)
• tsconfig.json baseUrl is now the root folder, as it is in the Angular CLI boilerplate project
• tsconfig.spec.json needs emitDecoratorMetadata: true (or access to program/type checker through ts-jest), see After upgrade Angular to v8: Can't resolve all parameters for Component: (?). #288
• Adjustment to make ng build --aot not fail: [\`styles\`]: ... had to become styles: ... again and declared all components to app.module
• Updated polyfills.ts to current one
• Updated all ts config files
• Updated ts lint config file

Note that most tested files and tests remained untouched. Mostly the Angular Project files were changed.
Is this breaking due to moving core-js to dependencies?

Renaming the example project to e. g. test-app would be another task I would like to start with after this PR.

I would like to keep #288 open, as the cleaner approach might be a transformer (one day).

Solves #266.

[wtho]

Just realized a changelog entry is still missing. Will add it soon!

[ahnpnl]

• I agree e2e should be removed. It is irrelevant for the example app.
• I think the versions of dependencies for test app can just be kept in package.json as they are now.
• I think now we include core-js in dependencies is a breaking in the meaning of preset scope. In the meaning of usage scope, it's not really a breaking since it doesn't break anything on users' side unless users uninstalled core-js (I don't think there are any polyfill libraries better than it)

[wtho]

There are polyfill libraries that are way more lightweight than core-js for the decorator metadata, but as it was a dependency of Angular for such a long time, we should still stick to it. Especially when the preset will be used with an older Angular version the users would have core-js installed already.

[wtho]

Last Force Push

• Added Changelog information
• Removed the e2e folder and e2e configuration file
• Updated basic information of the example app README.md to inform users what the example app is

[thymikee]

👍

[wtho]

Last Force Push:

• removed tslint dependency and configuration in the example app (was ignored and never run)
• rephrased changelog as recommended