make prefix configurable, and allow no prefix

[tacman]

Re: #17

I'd prefer to make the twig calls without the fn prefix. Or perhaps to prefix my application twig functions with app, for example.

It's awkward to need the fn, but since that's how it currently works, maybe you could make it configurable and default to fn , but allow none.

    # injected into twig via
    #[AsTwigFunction('source_icon')] # fn_source_icon
    static public function getSourceIcon(string $source): ?string

zenstruck_twig_service:
  functions:
    - iterator_to_array # available as "fn_iterator_to_array()" in twig
    - json_decode #fn_json_decode
    - file_exists

Could be

zenstruck_twig_service:
 prefix: false # or "" 
 functions:
    - iterator_to_array # available as "iterator_to_array()" in twig
    - json_decode # json_decode
    - file_exists

[tacman]

Thoughts on this, @kbond? Or am I doing something wrong? I think the documentation is wrong, but I'd rather the code change to match the documentation, as I'd like to get rid of the fn_ prefix.

[kbond]

I need the prefix because of the twig feature I'm using to achieve this: https://twig.symfony.com/doc/3.x/advanced.html#dynamic-filters

While possible to add these functions directly to twig, this would reduce performance - especially when adding many functions.