Fix nested struct array rule generation

[palinatolmach]

Follow up to #830.

This PR ensures that the elements of nested structs up to an arbitrary depth all have _{i} indices appended to their names if they correspond to an array element. It also factors out the processing of tuple array components into a separate function process_tuple_array.

This PR also adds a test that exercises the previously missing edge case, which manifested in variables on the LHS and in the ensures clause of the #abiCalldata rule in contract.k not having proper indexes (..._0) set.

Please note that this test branches on the possible length of dynamically sized strings in the calldata, so it is meant to test kontrol build and is not run during the kontrol prove stage:

// SPDX-License-Identifier: UNLICENSED
pragma solidity =0.8.13;

import "forge-std/Test.sol";

interface ProjectConfig {
    struct ChainEnv {
        string chainName;
        string chainIndex;
    }

    struct Vault {
        string tokenName;
        address oracle;
        uint256 allowedToTrade;
        InputData params;
        uint256 reserves;
    }

    struct InputData {
        uint256 ltv;
        uint256 rate;
        uint256 exchangeRate;
        uint256 utilization;
    }

    struct AssetAddresses {
        address cToken;
        address dToken;
    }

    struct VaultWithAddresses {
        Vault vault;
        AssetAddresses addresses;
    }
}

contract NestedStructArrayTest is Test, ProjectConfig {
    // this test branches on dynamically sized calldata and not run in CI; it is only meant to test `kontrol build`
    function testVaultSignature(ChainEnv calldata environment, VaultWithAddresses[] memory listings) external { 
        assert(listings.length == 1);
    }
}

[ehildenb]

😍 nice refactoring!

[anvacaru]

Nice! I was able to build my project using this fix