Add active class to the column menu icon once something in it is different from default

Currently we recommend using custom class on the header(https://www.telerik.com/kendo-vue-ui/components/grid/columns/column-menu/#toc-styling-the-column-menu-icon), yet not visualising that the menu is populated seems like a UI misleading issue when using the component so we should add it by default

Describe the bug
Locked and resized columns leave a small gap between the columns when scrolling is performed

To Reproduce
Steps to reproduce the behavior:
https://stackblitz.com/edit/mzxqs7-hy29kw?file=src%2Fmain.vue
lock both first and the second column from the column menu
resize the first column
scroll the columns

Curent -
A tiny gap is visible between the first and the second column

In the vue native grid, the inputs rendered in the filter row don't have a title or accessible name. This would make it nearly impossible for someone using a screen reader to understand what each field means. In order to comply with WCAG 4.1.2 (Name, Role, Value) please add a title and/or aria-label/labelledby attribute to these inputs. 

The jquery grid has the aria-label and title populated with the column name. I think it'd be even more useful if the label said "Filter by {columnName}".