ui: table - implement unit tests for TableColumn component

[christophercr]

I'm submitting a...

[X] Regression (a behavior that used to work and stopped working in a new release)
[ ] Bug report  
[X] Feature request
[X] Documentation issue or request
[ ] Support request => Please do not submit support request here, instead see https://github.com/NationalBankBelgium/stark/blob/master/CONTRIBUTING.md#got-a-question-or-problem

Current behavior

The StarkTableColumnComponent has no unit tests so far and there are important functionalities implemented in that component.

Expected behavior

Proper unit tests should be implemented for the StarkTableColumnComponent component to prevent bugs, which we already have, for example: #1468

What is the motivation / use case for changing the behavior?

Stable and well tested code.

Environment

Stark version: 10.0.0-beta.0 -> 10.0.0-rc.2