Added ChaCha20 Cryptographic Algorithm Implementation

[Susmita331]

This PR introduces the implementation of the ChaCha20 cryptographic algorithm, a high-speed and secure stream cipher widely used for encryption. The implementation includes:

The ChaCha20 quarter-round function

• Key scheduling and initialization of the ChaCha state matrix
• The generation of keystream blocks for encryption/decryption
• Support for nonce and counter-based operations

This addition enhances the cryptographic capabilities of the project, ensuring efficient and secure encryption suitable for various applications.

[Kishan-Ved]

The errors are due to no module named numpy

If you need it, try specifying it in requirements.txt

[czgdp1807]

This is the scheme of remote which I follow (you can follow your own),

origin - https://github.com/codezonediitj/pydatastructs
czgdp1807 - https://github.com/czgdp1807/pydatastructs
Susmita331 - https://github.com/Susmita331/pydatastructs

To update this PR, just commit changes in your branch and execute the following,

git push Susmita331 CryptoAlgorithm

How to resolve conflicts? Follow the steps below,

1. git checkout main
2. git pull origin main
3. git checkout CryptoAlgorithm
4. git merge main
5. Now resolve conflicts in VSCode
6. git add .
7. git commit -m "Merge main"
8. git push Susmita331 CryptoAlgorithm