Add nan as dev dependency to React templates

[captainsafia]

Description

nan is an npm package that provides some helpful APIs for building native add-ons for Node. This package is a dependency of fsvents, another npm package that is used to watch for filesystem changes on macOS. The webpack dependency used by create-react-app brings in an older version of fsevents into our transitive dependencies but doesn't properly install the nan dependency.

This issue causes the npm install step to error our in our react and react-redux templates on macOS (since fsevents is a macOS-only package and other templates bring in the nan package to the dependency tree via other transitive dependencies).

To resolve this, we include nan as a dev dependency in the templates to ensure that it is installed.

Customer Impact

This issue was discovered during manual testing. It only impacts react and react-redux templates running on macOS.

This bug breaks the dotnet run and dotnet publish steps in the template project because the npm install step is unable to complete successfully as a result of the missing dependency.

As a workaround, customers can install the nan dependency manually in their ClientApp directories.

Regression?

This change contains no regressions.

Risk

The risk level of this change is low because:

• nan is included as a dev dependency and shouldn't affect production or runtime environments
• this fix was validated on the react and react-redux templates

Addresses https://github.com/aspnet/AspNetCore-ManualTests/issues/100

[ghost]

Hello human! Please make sure you've included the Shiproom Template in a comment or (preferably) the PR description. Also, make sure this PR is not marked as a draft and is ready-to-merge.

[mkArtakMSFT]

Thanks @captainsafia!

[mkArtakMSFT]

This was approved already to be merged.

[dougbu]

Looks good though I think you meant indirect and not transient 😺