React wrapper: Add a check that only HotColumn instances are children of HotTable

[NOtherDev]

Context

The structure of components in React wrapper is now straightforward: HotTable contains zero or more HotColumn children and nothing else, and HotColumn never have children. Any other scenario is incorrect and throws a warning.

How has this been tested?

• all the unit tests + new unit tests for the feature passing

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature or improvement (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Additional language file or change to the existing one (translations)

Related issue(s):

1. Proposal in RFC

Affected project(s):

• handsontable
• @handsontable/angular
• @handsontable/react
• @handsontable/vue
• @handsontable/vue3

Checklist:

• I have reviewed the guidelines about Contributing to Handsontable and I confirm that my code follows the code style of this project.
• I have signed the Contributor License Agreement
• My change requires a change to the documentation.