[Feature]: Implement Blur Function in helpers.c

[harshsankhla18]

So, what is it about?

Apply a box blur by averaging the RGB values of a pixel’s 3×3 neighborhood.

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[indrasuthar07]

@harshsankhla18 Assign this to me I'll implement a function for blurring the images

[saumya1317]

Assign this to me