fix: allow response types to contain unexported fields

[FlorianLoch]

So far using a type as Body on a response type containing unexported fields results in a panic:

panic: reflect.StructOf: field "config" is anonymous but has PkgPath set

goroutine 1 [running]:
reflect.runtimeStructField({{0x105753038, 0x6}, {0x105778f34, 0x27}, {0x1059311a8, 0x1058b15e0}, {0x10575303f, 0x8}, 0x0, {0x14000352668, ...}, ...})
        /opt/homebrew/Cellar/go/1.22.0/libexec/src/reflect/type.go:2538 +0x1c8
reflect.StructOf({0x14000270008, 0x10, 0x14000548508?})
        /opt/homebrew/Cellar/go/1.22.0/libexec/src/reflect/type.go:2189 +0x274
github.com/danielgtaylor/huma/v2.(*SchemaLinkTransformer).OnAddOperation(0x140005a2150, 0x140005aa0b0, 0x14000548601?)
       .../huma/transforms.go:110 +0x2d0

As I am using ent (entgo.io) that is subpar, because the structs generated by ent contain unexported fields (in this case config, which triggered the panic above).
Creating proxy types would really break the experience, so it's not really an option.
And anyway I don't see why huma would not want to support such structs as it seems to me there is no drawback in this simple fix suggested - but as I am new to huma and its codebase I might just not see it 😉.

Feedback would be appreciated.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.70%. Comparing base (30fe05a) to head (34360bb).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #278   +/-   ##
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  Coverage   94.70%   94.70%           
=======================================
  Files          18       18           
  Lines        2700     2700           
=======================================
  Hits         2557     2557           
  Misses        105      105           
  Partials       38       38           

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[danielgtaylor]

This looks great, thanks! 👍