Add support for most random cheatcodes

[palinatolmach]

This PR partially addresses #876.

This PR adds support for the following cheatcodes recently added to forge-std, and adds end-to-end tests for them:

    /// Returns a random `address`.
    function randomAddress() external returns (address);

    /// Returns a random `bool`.
    function randomBool() external view returns (bool);

    /// Returns a random byte array value of the given length.
    function randomBytes(uint256 len) external view returns (bytes memory);

    /// Returns a random fixed-size byte array of length 4.
    function randomBytes4() external view returns (bytes4);

    /// Returns a random fixed-size byte array of length 8.
    function randomBytes8() external view returns (bytes8);

    /// Returns a random uint256 value.
    function randomUint() external returns (uint256);

    /// Returns a random `uint256` value of given bits.
    function randomUint(uint256 bits) external view returns (uint256);

    /// Returns random uint256 value between the provided range (=min..=max).
    function randomUint(uint256 min, uint256 max) external returns (uint256);

The following cheatcodes will be added in a follow up PR; they're currently causing branching due to some signed ints specifics:

    /// Returns a random `int256` value.
    function randomInt() external view returns (int256);

    /// Returns a random `int256` value of given bits.
    function randomInt(uint256 bits) external view returns (int256);