feat(cli): pass skip testing flag to application schematic

[yudin-s]

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?

[ ] Bugfix
[x] 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?

The v12 nest new --skip-tests flag passes spec: false to the application schematic. That skips spec files, but it does not give the schematic enough information to skip the full testing scaffold.

Issue Number: Refs #2575

What is the new behavior?

When --skip-tests is enabled, the new command now passes both spec: false and skipTesting: true to the application schematic. This preserves the existing spec-file behavior while allowing the schematic to omit test files, Jest configuration, testing scripts, and testing-related dependencies.

This pairs with nestjs/schematics#2354.

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

Validated with:

npm test -- test/actions/new.action.spec.ts
npm run build
npm run lint
npm exec -- prettier --check actions/new.action.ts test/actions/new.action.spec.ts
git diff --check

npm run lint completed with one existing warning in lib/runners/runner.factory.ts and no errors.