closes: ash-project#20

- introduces `store_inputs?` to the DSL
- `store_inputs?` if not included defaults to false
- when switched on it ensure an attribute is created to capture the exact
  inputs of each new version, when the resource we are paper-trailing changes.

When we use `store_inputs? true` we store the original inputs of the change as
map. Within this map all structs representing Ash Resources are converted into
a map using `Ash.Type.dump_to_embedded/3`.

We use the function `normalise_inputs/1` to do this which will deeply recurse
within maps and lists to ensure all Ash Resource have been converted into their
embedded counterpart.

This is a temporary measure, the eventual goal is to inspect each value in the
inputs, if that value is sensitive then we'll redact it from the inputs stored
in the version

…ords

Co-authored-by: Robert Graff <[email protected]>