[ENH] Implementing Adorn Functions

[Sarra99]

This PR resolves #993.

PR Checklist

Please ensure that you have done the following:

1. PR in from a fork off your branch. Do not PR from <your_username>:dev, but rather from <your_username>:<feature-branch_name>.

2. If you're not on the contributors list, add yourself to AUTHORS.md.

3. Add a line to CHANGELOG.md under the latest version header (i.e. the one that is "on deck") describing the contribution.
   • Do use some discretion here; if there are multiple PRs that are related, keep them in a single line.

Automatic checks

There will be automatic checks run on the PR. These include:

• Building a preview of the docs on Netlify
• Automatically linting the code
• Making sure the code is documented
• Making sure that all tests are passed
• Making sure that code coverage doesn't go down.

Relevant Reviewers

Please tag maintainers to review.

• @ericmjl

[codecov]

Codecov Report

Attention: Patch coverage is 95.71429% with 3 lines in your changes missing coverage. Please review.

Project coverage is 83.37%. Comparing base (6e77fbc) to head (97e786b).
Report is 45 commits behind head on dev.

Additional details and impacted files

@@            Coverage Diff             @@
##              dev    #1439      +/-   ##
==========================================
- Coverage   89.07%   83.37%   -5.70%     
==========================================
  Files          87       88       +1     
  Lines        5374     6444    +1070     
==========================================
+ Hits         4787     5373     +586     
- Misses        587     1071     +484     

[samukweku]

@Sarra99 kudos on your PR!!
kindly add more tests to ensure coverage is complete. The code shows the missing lines in your code that do not have coverage.

Thanks!!

[samukweku]

pinging @ericmjl and @pyjanitor-devs/core-devs

[ericmjl]

@Sarra99 would you be kind enough to decorate the functions here as a dataframe method, like we do in other files?