remove ability to generate more random values from interface

[moodysalem]

it should be clear from the interface that the randomness provider can only generate max 32 bytes of entropy per block, at least as currently implemented

zk-eth-rng/contracts/src/IRandomnessProvider.sol

Lines 23 to 24 in 70421ed

	/// @notice Returns >= 1 random values from a specific block.
	function fetchRandomness(uint256 blockNum, uint256 numberRandomValues) external view returns (uint256[] memory);

this interface may confuse the user of the randomness provider into thinking that they can get more entropy from a single block, when it's really just pseudorandom numbers generated from a seed. while this can be explained in docs, it's better to keep it out of the interface and just have a separate library for generating pseudorandom numbers from a seed imo

also the user may not want to use the method for generating pseudorandom numbers that is implemented in the randomness provider