fix: flatten asset definitions and assets in data model

[SamHSmith]

Description

Linked issue

Closes #{issue_number}

Benefits

Checklist

• I've read CONTRIBUTING.md
• I've used the standard signed-off commit format (or will squash just before merging)
• All applicable CI checks pass (or I promised to make them pass later)
• (optional) I've written unit tests for the code changes
• I replied to all comments after code review, marking all implemented changes with thumbs up

[mversic]

you have to fix this:

• on Unregister<Account> remove all entries from World::assets
• on Unregister<Domain> remove all entries from World::asset_definitions

[nxsaken]

Torii tests need to be updated, otherwise looks good

[Erigara]

Let me check smt.

EDIT:
As i said in my previous comment AssetIds are ordered by AssetDefinitionId first, so current usage of AssetByAccountBounds is not correct, because all assets for AccountId are not in the same adjacent to each other.

    #[test]
    fn asset_account_range() {
        let domain_id: DomainId = "wonderland".parse().unwrap();

        let account_id = gen_account_in("wonderland").0;

        let accounts = [
            account_id.clone(),
            account_id.clone(),
            gen_account_in("a").0,
            gen_account_in("b").0,
            gen_account_in("z").0,
            gen_account_in("z").0,
        ];
        let asset_definitions = [
            AssetDefinitionId::new(domain_id.clone(), "a".parse().unwrap()),
            AssetDefinitionId::new(domain_id.clone(), "f".parse().unwrap()),
            AssetDefinitionId::new(domain_id.clone(), "b".parse().unwrap()),
            AssetDefinitionId::new(domain_id.clone(), "c".parse().unwrap()),
            AssetDefinitionId::new(domain_id.clone(), "d".parse().unwrap()),
            AssetDefinitionId::new(domain_id.clone(), "e".parse().unwrap()),
        ];

        let assets = accounts
            .into_iter()
            .zip(asset_definitions)
            .map(|(account, asset_definiton)| AssetId::new(asset_definiton, account))
            .map(|asset| (asset, ()));

        let map = Storage::from_iter(assets);

        let view = map.view();
        let range = view.range(AssetByAccountBounds::new(&account_id));
        assert_eq!(range.count(), 2);
    }

[SamHSmith]

I swapped the internal order of AssetId to make it sort correctly. Api remains the same.

Sorting was fixed