[5.x] Ability to set custom Glide hash

[jasonvarga]

Alternate solution to #9781.

This PR lets you customer the unique hash in Glide-generated files.

By default, the hash is just literally just a md5 hash of the manipulation parameters.

You may want to customize it to make it more human readable for debugging or QA purposes as explained in #9781 or just because you prefer it aesthetically.

You can do this in your AppServiceProvider:

public function register()
{
    $this->app->booting(function () {
        Glide::generateHashUsing(function (string $source, array $params) {
            return collect($params)
                ->sortKeys()
                ->map(fn ($value, $param) => "$param-$value")
                ->join('-');
        });
    });
}

When generating a glide image like this:

{{ glide:myimage width="100" height="50" fit="crop" quality="50" }}

normally it would be generated to a path like this:

containers/assets/path/to/image.jpg/0638baede3a7fc1a91f605e095ab74cc/image.jpg

but with the custom closure it would get generated to this:

containers/assets/path/to/image.jpg/fit-crop-h-50-q-50-w-100/image.jpg

---

This PR also just does some minor cleanup and refactoring of the cachePath method.