try switching to structs

[iainnash]

1. Removes stack too deep error with coverage
2. Saves contract size
3. Makes return types in ABI easier to read (less confusing since they can be named).

Compiler run successful!
| Contract                | Size (kB) | Margin (kB) |
|-------------------------|-----------|-------------|
| Address                 | 0.058     | 24.518      |
| ECDSA                   | 0.058     | 24.518      |
| ERC1155                 | 5.423     | 19.153      |
| ERC1155RewardsStorageV1 | 0.184     | 24.392      |
| ERC721                  | 5.011     | 19.565      |
| Math                    | 0.058     | 24.518      |
| MockERC1155             | 8.239     | 16.337      |
| MockERC721              | 8.478     | 16.098      |
| ProtocolRewards         | 4.511     | 20.065      |
| ShortStrings            | 0.058     | 24.518      |
| SignedMath              | 0.058     | 24.518      |
| StdInvariant            | 3.679     | 20.897      |
| StdStyle                | 0.058     | 24.518      |
| StorageSlot             | 0.058     | 24.518      |
| Strings                 | 0.058     | 24.518      |
| console                 | 0.058     | 24.518      |
| console2                | 0.058     | 24.518      |
| stdError                | 1.348     | 23.228      |
| stdJson                 | 0.058     | 24.518      |
| stdMath                 | 0.058     | 24.518      |
| stdStorage              | 0.058     | 24.518      |
| stdStorageSafe          | 0.058     | 24.518      |

=== AFTER DIFF ====


> forge build --sizes
[⠆] Compiling...
[⠒] Compiling 7 files with 0.8.17
[⠑] Solc 0.8.17 finished in 16.90s
Compiler run successful!
| Contract                | Size (kB) | Margin (kB) |
|-------------------------|-----------|-------------|
| Address                 | 0.058     | 24.518      |
| ECDSA                   | 0.058     | 24.518      |
| ERC1155                 | 5.423     | 19.153      |
| ERC1155RewardsStorageV1 | 0.184     | 24.392      |
| ERC721                  | 5.011     | 19.565      |
| Math                    | 0.058     | 24.518      |
| MockERC1155             | 8.041     | 16.535      |
| MockERC721              | 8.283     | 16.293      |
| ProtocolRewards         | 4.511     | 20.065      |
| ShortStrings            | 0.058     | 24.518      |
| SignedMath              | 0.058     | 24.518      |
| StdInvariant            | 3.679     | 20.897      |
| StdStyle                | 0.058     | 24.518      |
| StorageSlot             | 0.058     | 24.518      |
| Strings                 | 0.058     | 24.518      |
| console                 | 0.058     | 24.518      |
| console2                | 0.058     | 24.518      |
| stdError                | 1.348     | 23.228      |
| stdJson                 | 0.058     | 24.518      |
| stdMath                 | 0.058     | 24.518      |
| stdStorage              | 0.058     | 24.518      |
| stdStorageSafe          | 0.058     | 24.518      |