When running `ng add`, the command will now not only check if a package has schematics but also verify that a schematic named `ng-add` is available in the collection.
This prevents cases where a package has a schematics entry in its `package.json` but does not contain the actual `ng-add` schematic, causing the command to fail.

...`ng add` functionality
When a user tries to `ng add` a package that doesn't provide its own `ng-add` schematic, the command will now check for a built-in schematic to use as a fallback.
This improves the user experience for popular packages that do not have native Angular CLI support. The first package supported is `tailwindcss`.