Implementation of hardcode_no_ct(), hardcode_ct(), assign_no_ct() and assign_ct()

[ramiromagno]

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[github-actions]

Package	Line Rate	Health
sdtm.oak	68%	➖
Summary	68% (447 / 662)	➖

[rammprasad]

Great start, Ramiro.

[edgar-manukyan]

Thank you so much @ramiromagno, very impressive work and smart reuse of coding logic. 💯 ⭐ ⭐ ⭐

I left few suggestions in the code and more questions for @rammprasad :)

Some items here as well:

• Assertions, just a kind reminder.
• Types of the parameters in the roxygen header, just a kind reminder.
• In the tests can we please have a ct dataset with more than one unique value
  of codelist_code? 🙏

[rammprasad]

Minor comments.

[rammprasad]

Works amazing. Minor comments. Ready to merge.

[rammprasad]

@edgar-manukyan @ShiyuC - Ready for the second review.

[edgar-manukyan]

Thanks so much @ramiromagno for an amazing work. 💯 ⭐ ⭐

Looks good to me and left some nice to have comments and thanks for opening issue #48 to increase the coverage 🙏