Move Lens overlay protos to third_party/lens_server_proto

Also, changes enum value CHROMIUM because it's a compile-time keyword

Bug: b/328480001
Change-Id: I21b2898aa35c092bfe384f813ba693d6fd961a9d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5394109


Reviewed-by: Rick Byers <rbyers@chromium.org>
Reviewed-by: Moe Ahmadi <mahmadi@chromium.org>
Commit-Queue: Jason Hu <hujasonx@google.com>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1280004}