Disallow default Cid and Address serialization

[austinabell]

Summary of changes
Changes introduced in this pull request:

• Just a sanity check as we get to the point of running a node
  • Default is only really needed out of convenience and for testing, but erroring on attempting to serialize either enforces that this default structs do not get used in any meaningful way.
  • Just makes debugging any potential bug relating to this easier as it will silently allow using the defaults currently

Reference issue to close (if applicable)

Closes

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