feat: add IsNotBlank decorator and corresponding tests

[gabriel-logan]

Description

Checklist

• the pull request title describes what this PR does (not a vague title like Update index.md)
• the pull request targets the default branch of the repository (develop)
• the code follows the established code style of the repository
  • npm run prettier:check passes
  • npm run lint:check passes
• tests are added for the changes I made (if any source code was modified)
• documentation added or updated
• I have run the project locally and verified that there are no errors

Fixes

fixes #[issue number], fixes #[issue number]

#543

IsNotBlank is a very important decorator and the lack of it is a big hindrance. I know it's easy to implement, but having it directly natively in the lib will certainly make things easier and please other devs.