Attribute Macro migration
#[migration]Expand description
A helper attribute for #[sdk_derive(...)]. It doesn’t do anything on its own;
it only marks functions that represent a module state migration.
The permitted forms are:
#[migration(init)]: Marks the initial (genesis) migration.#[migration(from = v)]: Marks a migration from version v to v+1, where v is a non-negative integer.