check_npx function added

[MasoumehSheikhi]

Title: Write a very short summary here

Problem: Write a description of your problem here.

Solution: Write a short summary of your solution.

Key Features:

• Key feature 1
• Key feature 2
• ...

Checklist

• [ ] Make sure you are requesting to pull a feature/bugfix branch (right side). This should not be main or develop.
• [ ] Make sure you are make a pull request against either main or develop (left side). (Requesting to main should be reserved for bugfixes and new releases)
• [ ] Add or update unit tests (if applicable)
• [ ] Check your code with any unit tests (Run devtools::check() locally)
• [ ] Add neccessary documentation (if applicable)

Type of changes

What type of changes does your code introduce? Put an x in the boxes that apply

• [ ] Bugfix (non-breaking change which fixes an issue) (link the issue on the right)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] Code style update (formatting, renaming)
• [ ] Documentation Update
• [ ] Other (explain)

Further comments

If this is a relatively large or complex change, kick off the discussion by explaining why you chose the solution you did and what alternatives you considered, any questions you have, etc...

Consider linking any issues (#issue-number ) or adding @mentions to ensure specific people see it.

[klevdiamanti]

Closing this PR as I have made several updates to the documentation of optimization_develop in the branch optimization_develop_roxugen. Will make a PR of opt_dev_checknpx_internal_funcs against optimization_develop_roxugen, and finally merge optimization_develop_roxugen to optimization_develop on PR #411.