[DX][META] Introduce functions similar to views_get_views_as_options() for other things

While working on https://github.com/backdrop-contrib/headless/issues/9, I noticed that we have views_get_views_as_options(), but there is no respective node_get_node_types_as_options() or taxonomy_get_vocabularies_as_options() etc.

We should introduce such functions to improve DX and provide consistency in code.