Settings Split: Add setting id for internal function keys setting

Bug: b/241965700
Change-Id: I1b8e121d9ba635539ed3b2694c54b0960e9f865d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4347743


Reviewed-by: Michael Checo <michaelcheco@google.com>
Commit-Queue: David Padlipsky <dpad@google.com>
Cr-Commit-Position: refs/heads/main@{#1118892}