Added --skip-npm-install option for NodeJS V4 programming model

[AlexPshul]

Issue describing the changes in this PR

This really helps in mono-repo scenarios in which the NPM install is not actually needed but takes a significant time to initialize a new project. (A proper warning is added if NPM installation is skipped) resolves #3332

Pull request checklist

• [x] My changes do not require documentation changes
  • [ ] Otherwise: Documentation issue linked to PR
• [x] My changes do not need to be backported to a previous version
  • [ ] Otherwise: Backport tracked by issue/PR #issue_or_pr
• [x] I have added all required tests (Unit tests, E2E tests)

[AlexPshul]

@microsoft-github-policy-service agree

[AlexPshul]

Hi @khkh-ms @mattchenderson , Is there anything else I need to do in this PR? Or is it ready for merging?

[khkh-ms]

/azp run

[azure-pipelines[bot]]

Azure Pipelines successfully started running 1 pipeline(s).

[AlexPshul]

Hi @khkh-ms thank you for continuing the process on this. I see that the build failed on 2 items and it seems to be unrelated to my changes:

• Azure.Functions.Cli.Tests.E2E.InitTests.init_with_Dockerfile(workerRuntime: "node", version: "4")
• Azure.Functions.Cli.Tests.E2E.DeploymentTests.RemoteBuildPythonFunctionApp

Is it something I need to handle on my side? Is there anything I can help with to help with the merge?