add_location: TxDescriptor<
    {
        cid: { digest: FixedSizeBinary<4>; geohash: FixedSizeBinary<5> };
        location: { lat: bigint; lon: bigint };
    },
>

Add a new meetup location to the community with cid.

May only be called from T::TrustableForNonDestructiveAction.

Todo: Replace T::CommunityMaster with community governance: #137.