fix(@angular/cli): handle npm-aliased and unfetchable packages in ng update

[maruthang]

Summary

• ng update would fail with a 404 error when package.json contains dependencies using npm aliases ("my-pkg": "npm:real-package@^1.0.0") or packages from private/non-npmjs registries
• The Promise.all() for fetching package metadata would reject entirely when any single package couldn't be fetched, even if it wasn't part of the update
• The fix filters out npm: aliased packages early (since the alias name differs from the real package name) and catches individual fetch errors gracefully, allowing the existing reduce logic to handle missing packages

Closes #28834

Test plan

• Run ng update on a project with npm: aliased dependencies — should complete without error
• Run ng update on a project with private registry packages — should skip unfetchable packages gracefully
• Run ng update @angular/core on a normal project — should work as before

[gemini-code-assist]

Code Review

This pull request enhances the Angular CLI update schematic to better handle npm aliases and metadata fetch failures by returning partial results on error. The review feedback recommends a more robust implementation for alias detection using the npa.resolve result type rather than a simple string prefix check.

[gemini-code-assist]

Using the result of npa.resolve to detect aliases is more robust than a manual string prefix check. This approach handles edge cases like case-insensitivity (e.g., NPM:) and potential whitespace consistently with how the rest of the package resolution logic operates.

Suggested change

	// npm: aliases (e.g., "npm:real-package@^1.0.0") resolve as registry packages
	// but the dependency key name differs from the actual package name, so registry
	// lookups using the alias name would fail with a 404.
	if (specifier.startsWith('npm:')) {
	return false;
	}
	const result = npa.resolve(name, specifier);
	return !!result.registry;
	// npm: aliases (e.g., "npm:real-package@^1.0.0") resolve as registry packages
	// but the dependency key name differs from the actual package name, so registry
	// lookups using the alias name would fail with a 404.
	const result = npa.resolve(name, specifier);
	return !!result.registry && result.type !== 'alias';