[Feature]: change package (type) to library and add autoload

### Current Behaviour and Context

Currently the helper methods are only available when the plugin is active which introduces a point of failure.
Context:
We have a few composer packages that have assets generated by webpack. We would really like to use your library to load them; but because it is a plugin we cannot do that easily, because the plugin might not be active.

### Improved Behaviour

By changing the package to a standard composer library package and adding autoload through composer.json the functions are guaranteed to be available.

### Additional Info

If there is a use case for keeping this as a plugin, it could be a possibility to build a wrapper plugin. We would be willing to help with PR's

Start with composer.json and the current plugin bootstrap to understand how the helper methods are exposed today. Change the package to a standard Composer library with autoloading, then verify that the helper functions are available without the plugin being active.

Written by the indexing model from the issue text.