feat(eda): add sort by for variables section in create_report

[khoatxp]

Description

Add the following sort by cases for the variables section in create_report()

• Original feature order
• Alphabetical (sort order default from a-z)
• Amount missing (sort order default from highest % missing to lowest % missing)

Add reverse order option for all of the above sort by cases

Note: For the changes in variables.html. I only added the section-sort div to the file, the rest is just indenting to match with the new div

How Has This Been Tested?

Tested manually by inspecting the report viewed on browser

Snapshots:

Checklist:

• [x] My code follows the style guidelines of this project
• [x] I have already squashed the commits and make the commit message conform to the project standard.
• [ ] I have already marked the commit with "BREAKING CHANGE" or "Fixes #" if needed.
• [x] I have performed a self-review of my own code
• [x] I have commented my code, particularly in hard-to-understand areas
• [x] I have made corresponding changes to the documentation
• [x] My changes generate no new warnings
• [ ] I have added tests that prove my fix is effective or that my feature works
• [x] New and existing unit tests pass locally with my changes
• [ ] Any dependent changes have been merged and published in downstream modules