preview: ensure we test with correct preview app

[dtopuzov]

Now we run all CLI tests with preview app in:

\\telerik.com\distributions\DailyBuilds\NativeScript\Playground\ns-play-dev\debug

Which is usually (not always) preview app build with next versions of packages.

When we test CLI from release branch we need preview with rc or latest packages.
Same applies for PRs in CLI repo.

Suggested steps for solving the problem:

• Change output location of ns-play-dev jobs
• Add job to build ns-play-dev with rc
• Make sure CLI tests consume the correct binaries for preview app (based on branch and/or phrase)