Created by: ysds
#29073 can not override specific cols width. This PR allows this. e.g.
<div class="row row-cols-4">
<div class="col">Column</div>
<div class="col">Column</div>
<div class="col-6">Column</div> /* override col width */
<div class="col">Column</div>
</div>https://deploy-preview-29317--twbs-bootstrap.netlify.com/docs/4.3/layout/grid/#row-columns
The difference from #29274 is that row-cols- still needs .col or .col- class for consistency with our traditional rule.