PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/nestjs/nest/blob/master/CONTRIBUTING.md
• 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?

[x] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[ ] Other... Please describe:

What is the current behavior?

Issue Number: #1115

What is the new behavior?

Using the right package manager to install packages (detecting by lock files)

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

As described in angular/angular-cli#24305, running the same schematic in angular-cli works correctly (using the right package manager)

ng new test --no-install
cd test
touch yarn.lock
ng g @nestjs/schematics:resource --name=users --no-dry-run --no-skip-import --language="ts" --source-root="src" --spec --no-flat

nest g and ng g are basicly the same, so we can fix this problem in cli level just like angular-cli.

If you look into angular's codebase (https://github.com/angular/angular-cli/blob/489d4df0ed17481492728624735a235f25a418db/packages/angular/cli/src/command-builder/schematics-command-module.ts#L116), the packageManager option is predefined in angular-cli and passed into a NodeWorkflow.

In nest-cli, we directly use a binary file from @angular-devkit/schematics-cli to run our schematics.

See PR: angular/angular-cli#24305