Bm/on-build-descriptors

[BenjaminMidtvedt]

Add some descriptors for methods that specify that those methods should be run on the build cycle.

This is intended for developers.

The main utility is that methods that live on the build life cycle are now guaranteed to operate on the final object. So these configurations are ensured to survive .new(). By default, only the operations done in __init__ and configure survive new.

In the future, it may be worth it to make configure such a hook as well.

Example:

class MyModule(DeeplayModule)
    @after_build
    def set(self, name, value):
        setattr(self, name, value 

module = MyModule()
module.set("foo", 10)

module.foo # AttributeError

module.build()

module.foo # 10