[$400 in kSQT] Migrate Snapshot Subgraph

[jamesbayly]

Migrate this Subgraph to a SubQuery project https://github.com/snapshot-labs/snapshot-subgraph

You must submit the resulting code as a contribution to https://github.com/subquery/ethereum-subql-starter/

See the migration guide here https://academy.subquery.network/build/graph-migration.html

The resulting code must build and run correctly and have strict mode enabled (strict: true in the TS config)

The resulting code must support all chains that the current Subgraph does, and leverage SubQuery's multi chain indexing function (e.g. it indexes all data into the same dataset) https://academy.subquery.network/build/multi-chain.html