feat: Add support for storing impact/co-benefits and sdgs related info in anchored metadata

[blushi]

Description

Closes: #63

We are still missing the actual data for the existing classes (in particular which co-benefits are measured or not) so waiting on that but the rest can be reviewed already.

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[blushi]

@wgwz I've created a follow-up issue for updating metadata: https://github.com/regen-network/regen-registry-standards/issues/69 so I think we can merge this as soon as this is approved, could you have a final look? thanks