Deprecated options on generations

[tilucasoli]

Use case

I'm deprecating some properties of a Spec, but I can't deprecate them directly through the code generation process because I'm using mix_generator to generate the attribute and the utilities.

Proposal

I thought on two different ways to solve this problem

First Proposal

Introduce a deprecated parameter in MixableProperty. When this parameter is set to true, it indicates that all properties generated in Attribute and Spec are deprecated.

@MixableProperty(dto:, utilities:, deprecated: String?)

Second Proposal

Create a new annotation "MixableDeprecated" that is more generic but causes the same effect. The advantage of this approach is that it can be used separately.