Attribute Macro hookable

#[hookable]

This macro is used to mark a function as hookable, without changing the signature. It generates some extra codes to support hooks, and registers the function to the inventory.

Not Supported:

• functions with generic types
• functions with self receiver
• functions returns references

Examples:

#[hookable("add")]
fn add(left: i64, right: i64) -> i64 {
   left + right
}