feat: add SHAKE hash generator interfaces

[st1020]

Thank you for your amazing work.

I noticed that in versions before 1.4.0, there used to be experimental functions called shake256generator and shake128generator for generating infinite-length hashes.

I think these two interfaces are very useful and necessary, especially for cryptography, so this PR hopes to restore them.

A typical application scenario is to generate high-quality random integers in a specified range. If I want the distribution to be as uniform as possible, it is best to use rejection sampling, and an infinite-length hash is very useful. The difference from using random directly is that I can use bytes as a seed, and the algorithm is standardized, so it can be easily reproduced in different languages.

[dipu-bd]

Thank you for the effort to send a PR. I am particularly fond of this project and contributing whenever I can in my free time.

I recently made a release that improves support for the random generation. Keccak generator is included there too. Please check out the latest changes and let me know your thoughts.

[st1020]

I checked the latest commit. But I still think this interface is necessary.

As I said before, in the field of random number generation, the difference between using an infinite-length hash and using random directly is that it can use bytes instead of numbers as seeds, and the SHAKE algorithm is standardized, so it can be easily reproduced in different languages.

In addition, an infinite-length hash is also very useful in the design of other cryptographic algorithms.

SHAKE in other languages ​​also often comes with an interface for generating infinite-length hashes, such as Rust sha3 crate and Python PyCryptodome library.

Adding this interface does not require much work and maintenance cost, so I think such an interface should be added. Please tell me what you think.

[dipu-bd]

In addition, an infinite-length hash is also very useful in the design of other cryptographic algorithms.

Since a infinte loop can be easily generated from the user side, I had removed the implementation of this special case. But it is good to have in the library itself.

I have modified your PR a little bit. Instead of adding generate method in the KeccakRandom itself, I moved it to the public generator methods.

[st1020]

Thanks for merging the PR. :)