Using duplicate shortcut scrolls to the bottom of the tree

[poirierlouis]

Problem:
Using CTRL + D / CMD + D on a selected widget will force scrolling at the bottom of the tree. This is not expected, the scroll offset should stay the same.

Lead:
Default behavior of key D is to scroll down at the bottom. Using event.preventDefault() should be enough to fix this issue.

Scrolling when key D is pressed is related to a11y of <mat-tree>. It will scroll to the next node starting with the letter D. This can be verified with other keys/letters.

First migrate to latest version of <mat-tree>, using levelAccessor/childrenAccessor instead of treeControl. As of 18.2.11, migration will not work as expected. Padding will not be updated by <mat-tree> when moving a node inside/outside an expandable node (see #29959).