Options: add a DeathLinkMixin dataclass to easily standardize death_link (#2355)

* Options: add a DeathLinkOption dataclass to easily standardize death_link

* rename to DeathLinkMixin

* Update worlds/messenger/options.py

Options.py

@@ -1110,6 +1110,11 @@ class PerGameCommonOptions(CommonOptions):
     item_links: ItemLinks
 
 
+@dataclass
+class DeathLinkMixin:
+    death_link: DeathLink
+
+
 def generate_yaml_templates(target_folder: typing.Union[str, "pathlib.Path"], generate_hidden: bool = True):
     import os