[lensoverlay] Add lns_mode param

Bug: 339515473
Change-Id: Ie620ae56864721dc05a8125be1651f6d9d143f95
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5531856


Commit-Queue: Jason Hu <hujasonx@google.com>
Reviewed-by: Duncan Mercer <mercerd@google.com>
Cr-Commit-Position: refs/heads/main@{#1300693}