fix(dashboard): Take the keyboard button away when Edge misses an attach
On a Surface Pro 8 with Edge, detaching the keyboard brought the
floating keyboard button and attaching it again left it there. The
button goes on a fine primary pointer, which Edge reports on an attach
with its change event; after this attach either the pointer stayed
coarse or the event never came.
The page now reads the pointer query again on every resize, which each
posture brings (the taskbar), and on each mouse or touchpad event, so a
change without its event still counts. On a touch screen whose pointer
has been fine, a convertible, the touchpad in use says its keyboard is
back, as a keyboard-only key does: it lasts while the touchpad is used,
and a touch after the idle period or the pointer turning coarse takes
it back. A mouse on a screen whose pointer was never fine says
nothing, and the dashboard's own keyboard control outweighs the
touchpad until the pointer turns fine again.
hardware_keyboard_audit: 29/29 (the module before this fails it);
test_touch_controls.py x11 keyboard: 155/155, the posture block's
three new checks in every layout on Chromium, Firefox and WebKit; unit
tier 62/62.