Request the focus on the QuickSettingsContainer when it shows

This CL requests the focus on QuickSettingsContainer when it shows. Then
the user only needs one tab key press to move focus on the QS toolbar's
profile button.

Without this change, the first several tab presses do not trigger any
focus ring, which is confusing.

Bug: 443126358
Flag: EXEMPT bugfix
Change-Id: I9d257f4a545df0632758dd03dad200eb9195beec