Ionic Generate Application within existing Application

# Feature Request

**Ionic version:**

[x] **4.x**

**Describe the Feature Request**

Please provide the ability to generate a workspace and new libraries and applications within the workspace. I am asking for capabilities equal to "ng generate application", "ng new", and "ng generate library". This would allow people to generate a workspace and multiple projects within the workspace, and shared libraries.
Currently when "ng generate application" is run within an app created with "ionic start" an error is given:

> Schematic "e2e" not found in collection "@ionic/angular-toolkit".

No error is given when "ng generate library" is used within an ionic app and code is generated in the "projects" directory, though I am unsure if the code is correct and useful.

**Describe Preferred Solution**

Either allow "ng generate application" and "ng generate library" to work within an ionic project or create new commands to generate a workspace, library, and sub-application from the ionic cli.

**Additional Context**

Related issue: https://github.com/ionic-team/ionic-cli/issues/3087
Reference:
https://angular.io/cli/new
https://angular.io/cli/generate
https://angular.io/guide/file-structure#project-folders-for-additional-apps-and-libraries