refactor: move to Angular CLI based repository

[sarunint]

Checklist

• Issue number for this PR: ivy-ngcc is unable to compile AngularFire due to AngularFire not following APF #2021 (required)
• Docs included?: No
• Test units included?: Not done yet
• In a clean directory, yarn install, yarn test run successfully? Not yet

Description

Move to Angular CLI-based repository as discussed in #2021.

Code sample

N/A

@jamesdaniels this is just a PoC. You can run ng build but not ng test yet. Also @angular/fire/firebase-node is not moved yet. PTAL

[sarunint]

Note: currently, this PR is in all one big commit. But I'm happy to split it up later.

[jamesdaniels]

Adding @mgechev as we've been talking about switching this lib over to Bazel.

Thoughts on switching over to packagr?

[mgechev]

Ideally, we'll switch the CLI to Bazel just by replacing the builder in angular.json and this shouldn't impact AngularFire. If this PR leads to significant simplification of the build process, IMO, it's worth it.

[jamesdaniels]

@sarunint thanks for getting the ball rolling here. I'm taking up the work in #2117 as the slow builds are getting frustrating.