fix: extends correctly tsconfig.json from tsconfig.spec.json

[Fatme]

Currently when new code shared app is created, tsconfig.spec.json is created with incorrect content. It is looking for one directory up for its base tsconfig.json file. Actually both tsconfig.spec.json and tsconfig.json files are at the root level of the application.

Rel to: #243

PR Checklist

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• Tests for the changes are included.

What is the current behavior?

ng test command doesn't work for code shared applications

What is the new behavior?

ng test works for code shared applications

Fixes/Implements/Closes #[Issue Number].