[WIP] migrate unmigrated claims

[jam10o-new]

Rel: #932, #910

236 accounts on
the claims pallet currently remain unmigrated because they were omitted from claims.scale

This PR reintroduces migration code to migrate these accounts.

TODO:

• identify 236 accounts from the polkascan scrapes which need to be migrated (235 have been identified so far, remaining one does not appear to correspond to any known DOT allocation on ethereum.) EDIT: the accounts
• convert identified accounts into a claims.scale file.

Alternatively to this PR: we can call batch mint_claims for these accounts, and kill their old keys.

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[bkchr]

Couldn't this be done by an council motion that sets the data in the storage directly?

[jam10o-new]

I'm personally okay with minting new claims and killing all old keys in a batched extrinsic

[emielsebastiaan]

I am okay with that too as long as we are 100% transparent about what happened. That seems like the easiest way to make those impacted happy (again). That said, I’ll leave it to the experts.

[jam10o-new]

closing in favor of a council proposal