Do we need a helper like `has_bundler()`?

[simonpcouch]

The has_bundler() helper intends to help answer the question "will calling bundle() on x make use of any native serialization methods?"

e.g., has_bundler(x) would be TRUE is x was an xgboost fit or a workflow with a step_umap in its recipe, but FALSE if x is a workflow with an lm and a formula recipe.

I thought this sort of machinery would be useful for navigating the butcher/bundle interaction, but it turns out that butchering before bundling seems to always be fine, at least so far (#28).

I'm no longer sure whether we need a helper like has_bundler().🤔

[juliasilge]

I think that this would not be something a user would typically need to do, and for more developer-type tasks, we can check if we have specific methods().

What would you think about removing this from the initial release? We could add a vignette like the one for butcher that makes a nice table of everything that is supported.

[simonpcouch]

On board! I'll:

• [x] close #30
• [x] put in a PR to remove the helper
• [x] put in a PR to add a vignette like the one you've described