arc/gio: Change the nudge view base class for AlphaV2

Update education nudge for AlphaV2.
- Change the nudge view based on LabelButton instead of PillButton.
  Because PillButton sets its own corner radius and hard to override it.
- Add dot next to the menu entry button when showing nudge view.
- Update the size of the nudge view.

Bug: b/2646997380
Test: manual test to see if the nudge view shows up
Change-Id: I61d1b1a063f767622fabe23270d7da33579e88ff
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4226802
Auto-Submit: Cici Ruan <cuicuiruan@google.com>
Reviewed-by: David Jacobo <djacobo@chromium.org>
Commit-Queue: Cici Ruan <cuicuiruan@google.com>
Cr-Commit-Position: refs/heads/main@{#1104771}