Add image sharpening algorithm

[harshitpant1]

Description

Image sharpening is a practice used frequently in fields like astronomy, printing industries and many other areas of image processing. This PR adds image sharpening functionality (using unsharp masking algorithm) for grayscale and RGB images to GIL.

References

Principles of Digital Image Processing: Fundamental Techniques by Wilhelm Burger, Mark J. Burge.

Tasklist

• [ ] Add test case(s)
• [ ] Ensure all CI builds pass
• [ ] Review and approve

[harshitpant1]

Note that for this to work, https://github.com/boostorg/gil/pull/577 needs to be looked into first. Gentle reminder to @lpranam