Add a way to call this module if it is not the default dumper

Problem/Motivation

Our default dumper is Symfony var-dumper, but our front-end developers still want to be able to call kint.
The devel module allows that by providing a kint() Twig function: https://git.drupalcode.org/project/devel/-/blob/1a7e225762cd4485987d4376...

Steps to reproduce

1. Install devel_kint_extras.
2. Do not set Kint extended as the default dumper.
3. You can not call kint and make it display class methods.

Proposed resolution

We could add a new Twig function that calls the kint_extended dumper manually.

Remaining tasks

I will submit a patch.