[12.x] Make Vite asset path generation extendable via inheritance

[daun]

A much trimmed-down version of the proposed change in #57289 which was (rightly) rejected as feature creep.

This adds nothing but only makes the Vite class more extendable via inheritance. It moves the public path generation of Vite assets into a protected method. Any custom setups can extend the Vite class and overwrite this method.

Example usage (remove query string hash before generating disk path):

->withSingletons([
    Vite::class => fn() => new class extends Vite {
        protected function publicPath($path) {
            return parent::publicPath(Str::before($path, '?'));
        }
    }
])