Tree: multi-character search

[bill]

Add feature to traverse Tree nodes by typing multiple characters sequentially.

For example, in ​test_Tree.html

1. Select click on "Continents" node and make it in an expanded state
2. Type "a".
   • This moves focus to "Africa" (expected behaviour)
3. Type "u" immediately after step 2
   • Desired behavior : moves to "Australia"
   • Current behavior : focus stays in "Africa"

Windows Explorer and Eclipse Navigator view have such capability, but it is missing in dijit.Tree.

Apparently Windows Explorer clears the "input so far" queue if the user hasn't typed anything for (about) one second.

Highlighting what the user has typed so far would also be a possibl enhancement but is not necessary (windows explorer doesn't do this).

[DS]

Most customers value type ahead for usability. This would be good to fix/implement. Our product uses this widget.

[alex]

I'd also like to vote for this, perhaps also as a way of filtering (think FilteringSelect?, only using tree nodes as items, with the indentation visible in the "filter" view, but not the intermediate nodes).

[bill]

(In [18378]) Support multi-character search in tree, so that (for example) typing "As" will navigate directly to Asia, skipping over Africa. Fixes #8916 !strict.