Split fheRand and fheRandBounded in two functions

[immortal-tofu]

There is a need to get the seed in contract which extends TFHEExecutor.sol (for event). For this, we need to split the generation of the seed and the generation of the randomness in two functions. It will be easier to override the function.

We need to do it for fheRand and fheRandBounded.

    /* TFHEExecutor.sol */
    function fheRand(bytes1 randType) public virtual override returns (uint256 result) {
        seed = generateSeed();
        result = generateRand(randType, seed);
    }

    /* TFHEExecutorWithEvents.sol (Overloaded function for events) */
    function fheRand(bytes1 randType) public virtual override returns (uint256 result) {
        seed = generateSeed();
        result = generateRand(randType, seed);
        emit FheRand(randType, seed, result);
    }

[jat9292]

We need a similar generateRandBounded

[jatZama]

Done in #211