feat(@schematics/angular): add watch script for SSR in package.json

[bampakoa]

Add a watch script to run node in listen mode similar to the watch script for the client application.

PR Checklist

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• The commit message follows our guidelines: https://github.com/angular/angular-cli/blob/main/CONTRIBUTING.md#-commit-message-guidelines
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PR Type

What kind of change does this PR introduce?

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

What is the current behavior?

Issue Number: N/A

What is the new behavior?

Does this PR introduce a breaking change?

• Yes
• No

Other information

[alan-agius4]

Thanks for this, but for watch mode, ng serve should be used even when using SSR.