Use functional options for resourcex.Unmarshal

[danielrbradley]

Currently, the call normally looks like:

res, err := resourcex.Unmarshal(&typedInputs, inputs, resourcex.UnmarshalOptions{})

This would be a little neater if using functional arguments such as

func resourcex.Unmarshal(target interface{}, props resource.PropertyMap, opts... resourcex.UnmarshalOption) (resourcex.UnmarshalResult, error)

as then the minimal usage would be:

res, err := resourcex.Unmarshal(&typedInputs, inputs)

This would also avoid possible breaking changes on the public interface later on.

[iwahbe]

I'm not 100% sure I agree here. Passing several options looks like this now:

res, err := resourcex.Unmarshal(&typedInputs, inputs, resourcex.UnmarshalOptions{
    ForbidSecrets: true,
    RelaxTyping: true,
    AttemptMagic: true,    
})

I think ☝️ looks cleaner then:

res, err := resourcex.Unmarshal(&typedInputs, inputs,
    resourcex.ForbidSecrets,
    resourcex.RelaxTyping,
    resourcex.AttemptMagic,
})

Neither options are breaking. I think the big win is being able to call resourcex.Unmarshal(&typedInputs, inputs) as is. The loss is the trivially inspectable and portable bundle of options.