docs: add tree grid scroll to item section

[ugur-vaadin]

Adds scrollToItem feature to Tree Grid "Programmatic Scrolling" section.

[github-actions]

AI Language Review

1. In the DataService class:

   • The method getPeople(int count, Integer managerId) erroneously calls getPeople(managerId) which returns a list of employees for a given manager, not the complete list of people. This could lead to an incorrect sublist if the managerId is incorrect or if the count exceeds the number of people under that manager. Consider refining the logic or updating the method signature according to its intended purpose.

2. In the AsciiDoc documentation:

   • In the "Programmatic Scrolling" section, under "Scrolling to an Item by Path," the description lacks clarity on how the index array translates into scrolling actions. Consider further elaborating on the example to clarify how the hierarchical path translates into navigation actions within the grid.

[vursen]

Suggested change

	To use this feature, you need to specify the path of the item you want to view. The scroll position of the grid is adjusted to bring that item into view.
	You can also scroll to an item by providing its hierarchical path – an array of indexes where each index refers to a child of the item at the previous index. For example, to scroll to the second child-row (index 1) of the third root-level row (index 2), you would provide the path 2, 1.
	Scrolling continues until it reaches the last index in the array or encounters a collapsed item.

[ugur-vaadin]

Applied suggestion.