Hi Team,

I would like to request the toolbar data validation tool like this Kendo UI for jQuery demo to be included in the new Angular component. 

Thank you!

Provide the ability to customize the cells' content of the Spreadsheet. SImilar to the custom cell editors of the Kendo jQuery Spreadsheet:

https://demos.telerik.com/kendo-ui/spreadsheet/custom-editors

I have a project that uses Kendo UI for jQuery to work with spreadsheets. I want to recreate the project from scratch in Angular using the Kendo UI for Angular Spreadsheet component.

In jQuery, I am currently using `kendo.spreadsheet.defineFunction()` (docs) to define our custom functions and I would like to do the same in Angular.