Rename Picker related classes to QuickInsert.

Commands:

find ash/quick_insert/ -type f | \
  xargs perl -pi -e 's/(\b)Picker([A-Za-z]+)/\1QuickInsert\2/g'
find chrome/browser/ui/ash/quick_insert/ -type f | \
  xargs perl -pi -e 's/(\b)Picker([A-Za-z]+)/\1QuickInsert\2/g'
find ash/quick_insert/ -type f | \
  xargs perl -pi -e 's/cros_events::QuickInsert/cros_events::Picker\1/g'

Bug: b:369942539
Change-Id: Ic2b36792d0aee8bd9b8dce58213917b6920711fd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5995910
Reviewed-by: Michael Cui <mlcui@google.com>
Commit-Queue: Darren Shen <shend@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1381563}