feat(Row): Add row columns support

[kyletsang]

• Bug fix
• New feature
• Chore
• Breaking change
• There is an open issue which this change addresses
• I have read the CONTRIBUTING document.
• My commits follow the Git Commit Guidelines
• My code follows the code style of this project.
• My change requires a change to the documentation.
• • I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.

This is the new row columns feature from Bootstrap 4.4:
https://getbootstrap.com/docs/4.4/layout/grid/#row-columns

[TheSharpieOne]

Thoughts on removing the col prefix? Basically <Row colMd="3"> vs <Row md="3">, but it would also simplify the code a bit so that the mapping is not needed.
As it is now, you can pass in widths, but it always maps to those mappings. The reason widths exists it to allow for users to more easily define custom breakpoints like xxs or xxl (bootstrap's sass allows for this easily). Settings widths to ['xxs', 'xs', 'sm', 'md', 'lg', 'xl', 'xxl'] would allow this, but in the current code it would break since i would be of the rowColsPropsWidthMapping indexes (as well as mismatch)

[kyletsang]

Sure, I will make those changes right now.

[TheSharpieOne]

looks good. Thanks!