Feat/pixelate filter

[swastijain132005]

Description

Adds a new Pixelate filter (-P flag) that applies a mosaic effect.
The image is divided into small square blocks (default 5x5), and each block is replaced with its average color. Useful for artistic effects or privacy masking.

Semver Changes

• Patch (bug fix, no new features)
• Minor (new features, no breaking changes)
• Major (breaking changes)

Issues

Closes #25

Checklist

• I have read the Contributing Guidelines
• My code follows the project style guidelines
• I have tested the filter locally and verified it works correctly

[harshsankhla18]

The logic seems to be write but the curly braces is mismatching . Run the code and then raise the PR again with the desired output in the folder

[harshsankhla18]

@swastijain132005 please review this again

[harshsankhla18]

@swastijain132005 Resolve all conflicts and attach an output image and additionaly dont write anything after B: in the filters string , if you want to add any commandline letter like P write just before the character B in the string to avoid potential errors. Then I will accept the PR. Do it by tommorow.