fix(schematic): v8 support in AppModule

[geromegrignon]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/scullyio/scully/blob/master/CONTRIBUTING.md#commit
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Other... Please describe:

What is the current behavior?

When using ng add @scullyio/init into a v8 project, the schematic checks the version to add the right dependency into the package.json file but it doesn't check it to add the right import into the AppModule file.
Resulting having :

// package.json
'@scullyio/ng-lib-v8'

// AppModule.ts
import { ScullyLibModule } from '@scullyio/ng-lib'

Issue Number: #419

What is the new behavior?

The schematic checks the angular version of the project for the import added into the AppModule file.

Does this PR introduce a breaking change?

• Yes
• No

Other information

The PR removes a legacy test based on #242 action