Column template fix

[gabrielmontagne]

Description

A bug in the cells component was preventing the usage of templates on the column configuratin. The fix was very simple. I've also added a usage example on the basic-config example, as well as to the basic config block here,

https://bl.ocks.org/gabrielmontagne/61bf45ef534990696005d88bfcabb164

Motivation and Context

Per-column template is something that the grid supposedly supported, but a few experiments highlighted a bug that caused a RE.

How Was This Tested?

Manually on the embeded example rig, as well as on the block linked above.

Types of changes

• [x] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)

  Checklist:

• [x] My change follows the style of this project
• [ ] My change requires a change to the documentation
• [ ] I have updated the documentation accordingly
• [x] I have read the contribution guidelines
• [ ] I have added tests to cover my changes
• [ ] All new and existing tests passed