Test: tree/list navigation commands

[bpasero]

• win @roblourens
• os x @mjbvz
• linux @isidorn

Refs: #11517

We introduced new commands (see below) to make working with trees and lists more configurable for keyboard centric users.

• verify for all adopters (see below) that the keybindings are working and you can also change them (e.g. take the example of a VIM user that wants to use j, k, l, i for navigation in the tree
• verify you are not getting into a state where keys suddenly do not work anymore even though the tree/list has focus (interesting corner cases: rename box in files explorer)

Here is a list of new commands that will work in every tree and list (unless specifically overridden, for example the files explorer on macOS does not open on Enter, but rather goes into rename mode. instead, Cmd+Enter will open from the explorer):

Command	Keybinding
list.focusUp	kbstyle(Up Arrow) (additionally on macOS: kbstyle(Ctrl+P))
list.focusDown	kbstyle(Down Arrow) (additionally on macOS: kbstyle(Ctrl+N))
list.focusFirst	kbstyle(Home)
list.focusLast	kbstyle(End)
list.focusPageDown	kbstyle(PageDown)
list.focusPageUp	kbstyle(PageUp)
list.collapse	kbstyle(Left Arrow) (additionally on macOS: kbstyle(Cmd+Up Arrow))
list.expand	kbstyle(Right Arrow)
list.clear	kbstyle(Escape)
list.select	kbstyle(Enter) (additionally on macOS: kbstyle(Cmd+Enter))
list.toggleExpand	kbstyle(Space)

Adopters:

• Files Explorer
• Opened Editors
• SCM Viewlet
• Problems
• Quick open (use tab to jump into tree)
• Search (pay attention that you still see search results opening while you navigate through results)
• Extensions List
• Extension Dependencies (e.g. try with "Azure Pack")
• Debug Hover (click into it to give focus)
• Debug Variables View
• Debug Watch Expressions
• Debug Call Stack
• Debug Breakpoints
• Debug Repl (click into to give focus)