Add LCPPMultipleKey config

Bug: 328487899
Change-Id: Ie69b5c13563cc73c2cc491349f4ef447d9715398
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5394854


Reviewed-by: Minoru Chikamune <chikamune@chromium.org>
Commit-Queue: Yoichi Osato <yoichio@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1280119}