Feature/pkcs7 padding

[Kalkwst]

This pull request introduces a new class that implements the PKCS7 padding algorithm. The class provides three main methods: AddPadding, RemovePadding, and GetPaddingSize.

• AddPadding: This method adds padding to the end of a byte array according to the PKCS#7 standard.
• RemovePadding: This method removes the PKCS7 padding from the given input data.
• GetPaddingSize: This method gets the number of padding bytes in the given input data according to the PKCS7 padding scheme.

The implementation uses bitwise operations to avoid branching, which can lead to more efficient code execution,and avoid timing attacks.

In addition, a new folder structure Crypto/Padding has been created for this implementation, as the current structure didn’t have any relevant folder for this implementation.

• I have performed a self-review of my code
• My code follows the style guidelines of this project
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Comments in areas I changed are up to date
• I have added comments to hard-to-understand areas of my code
• I have made corresponding changes to the README.md

[codecov]

Codecov Report

Attention: 2 lines in your changes are missing coverage. Please review.

Comparison is base (5d9c5fe) 95.90% compared to head (5e815e2) 95.90%.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #406   +/-   ##
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  Coverage   95.90%   95.90%           
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  Files         221      222    +1     
  Lines        9200     9258   +58     
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+ Hits         8823     8879   +56     
- Misses        377      379    +2     

Files	Coverage Δ
Algorithms/Crypto/Paddings/PKCS7Padding.cs	96.55% <96.55%> (ø)

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[Kalkwst]

the naming convention change to Pkcs7Padding to me seems less readable than the PKCS7Padding, but I will change it to appease codacy

[siriak]

Looks good, thanks! As for the naming convention, it's a common convention to only capitalize the first letter of an acronym (e.g., https://learn.microsoft.com/en-us/dotnet/api/system.security.cryptography.aes?view=net-7.0)