GNS contract support

[sahra-karakoc]

• Curator: totalNameSignalledTokens, totalNameUnsignalledTokens
• GraphNetwork: totalTokensSignalledAutoMigrate, totalTokensSignalledDirectly

[juanmardefago]

After checking this, the existing GNS/Curation branch was missing the fields mentioned by @sahra-karakoc in this issue, and the existing code of that branch was already refactor and added to the substream after we started figuring out storage_changes (thanks @sahra-karakoc for the refactor!).

Even though, it seems this isn't crucial for indexer-agent or gateway usage, so I wouldn't count this as super high priority.