[Accessibility]: Fix keyboard shortcut workflow in Layers tool
[Accessibility]: Fix keyboard shortcut workflow in Layers tool

Issues:
- The treeoutline in the sidebar steals focus when clicking inside the canvas
- Even though the revealAndSelect call has the omitFocus property set to true, the treeOutline retains focus due to https://source.chromium.org/chromium/_/chromium/devtools/devtools-frontend/+/ede1b93b2ca1f3eebcd0ceae063cabef56cbb7c3:front_end/ui/legacy/Treeoutline.ts;l=1076;drf=front_end%2Fui%2Ftreeoutline.js;drc=ffa7862d4e6a0baa7e7c890436480bf3b7097e05;bpv=1;bpt=0
- Since the treeoutline has focus, none of the keyboard shortcuts work

Changes:
- When clicking on the canvas, first set focus on the canvas and then call revealAndSelect.

Note the focus indicators in these GIFs:
Broken: https://imgur.com/C82msmM
Fixed: https://imgur.com/9eHqU7K

Bug: 1205279
Change-Id: I8d961cb0fb33dd7b98d9b6d6a6bf9d096f65c5d2
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/2895462
Reviewed-by: Changhao Han <68542faf32f0a558a873c0f094ca9bedb2744bff@chromium.org>
Reviewed-by: Songtao Xia <efb39a3e57dd0e7c4fd137171d5e7a3f041d1da6@microsoft.com>
Commit-Queue: Michael Liao <00d75d81082fdf74688ec453c516b42f7cbf0f40@microsoft.com>

ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend