Add resourcex.Marshal

[danielrbradley]

Add a mirror version of the Unmarshal method to turn a struct into a resource.PropertyMap.

As an optional extension, this would be great if it supported setting secrets and unknowns in a way that is also returned by the Unmarshal method e.g.

resourcex.Marshal(typedInputs,
  marshalOption.WithSecrets("prop.subProp"),
  marshalOption.WithSecretPaths(resource.PropertyPath{"prop", 0, "subProp"}),
  marshalOption.WithUnknown("prop.propWithoutValue"))

[iwahbe]

This essentially already exists, it's just not exposed.

The Unmarshal function is:

pulumi-go-provider/infer/internal/ende/ende.go

Lines 28 to 38 in 9fbffb6

	// Decode a property map to a `pulumi:"x"` annotated struct.
	//
	// The returned mapper can restore the metadata it removed when translating `dst` back to
	// a property map. If the shape of `T` matches `m`, then this will be a no-op:
	//
	// var value T
	// encoder, _ := Decode(m, &value)
	// m, _ = encoder.Encode(value)
	func Decode[T any](m resource.PropertyMap, dst T) (Encoder, mapper.MappingError) {
	return decode(m, dst, false, false)
	}

The resulting encoder does lossless marshaling with all marshalOptions applied:

pulumi-go-provider/infer/internal/ende/ende.go

Line 291 in 9fbffb6

func (e *ende) Encode(src any) (resource.PropertyMap, mapper.MappingError) {