Parallel.ForEach should not be used for IO bound tasks

[surenderssm]

Summary

Showcase the power of Parallel.ForEach for CPU intensive operations.
Currently in docs example "How to: Write a simple Parallel.ForEach loop", IO bound operation is being used in Parallel.ForEach example, which is an anti-pattern.

With this change we are processing 2 million integers for PrimeNumber (CPU - intensive operation).
Case - I : Iterate over inputs via For loop.
Case - II : Iterate over inputs via Parallel.ForEach.

Print the time taken by both the cases.
Looking at time taken by both the cases, it is very evident how one can speed up execution by putting Paralle.ForEach to the right use.

Fixes #22232

Output from program

[dnfadmin]

All CLA requirements met.

[surenderssm]

@IEvangelist - This being my first PR in this repo, I will need some help with initial feedback and how to fix few of these checks which have failed.

[IEvangelist]

Hi @surenderssm - This looks good, thank you. We'll when you make the suggested changes.

[surenderssm]

Hi @surenderssm - This looks good, thank you. We'll when you make the suggested changes.

@IEvangelist - Thank you for the review comments. I have acted upon the same.
Let me know your thoughts on the change.

Snippet of returned result from the updated code.

[IEvangelist]

Looks good to me, we'll - thank you 🙏

[BillWagner]

closing and reopening for a fresh build