2.0: Align placement of erros between generic and other actions

Seems like currently default placement for errors in in a result. Except for generics, they put errors at the top level by default.

Makes sense to align them to the same default in next Ash version.

Start by comparing the default error placement for generic actions with the placement used by other actions in the GraphQL results. Trace the relevant defaults and existing coverage, then confirm that both paths produce errors at the same level in the next Ash version.

Written by the indexing model from the issue text.