Make assets:install smarter with symlinks

| Q             | A
| ------------- | ---
| Bug fix?   | no
| New feature?      | yes
| BC breaks?      | no
| Deprecations?      | no
| Tests pass?      | -
| Fixed tickets     | #11297
| License     | MIT
| Doc PR | -
I think I'd like even more information here, especially if the symlinks fail. Perhaps something like:

```php
if ($autoSymlinkFailed) {
    $output->writeln('It doesn\'t look like your system supports symbolic links, so the assets were installed by copying them');
} else {
    $output->writeln('The assets were installed using symbolic links');
}
```