Implementation of Sticky Header Feature in TreeGrid Completed

The Sticky Header feature in Syncfusion's ejs-treegrid component ensures that the column headers remain visible and fixed at the top of the grid while the data rows are scrolled vertically. This enhances the user experience by allowing users to continue viewing the header information (like column titles) as they scroll through large datasets. This is particularly useful in grids with many rows, where keeping track of column headers is essential for context. The sticky headers stay in place, even as the content below them moves, providing a seamless and intuitive interface for users interacting with extensive data.