Reland "Restrict visibility of libpng to current users"

This is a reland of commit 30284c444a33749e2a4396f9f047b090b7089a34

Original change's description:
> Restrict visibility of libpng to current users
>
> No new dependencies should be added on libpng: it is actively being
> migrated to a rust version, and image processing calls should go through
> skia instead of calling libpng directly. This CL enforces that by
> restricting the visibility of libpng targets to the current set of
> users, meaning any new users will require owners approval.
>
> The separate visibility file serves as an easily-auditable record of
> who is currently depending on libpng, and how that changes over time.
>
> Bug: 433723342
> Change-Id: I9e0c94fa1547c1478b849325aa6914e92bfaff9e
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6777532
> Commit-Queue: Devon Loehr <dloehr@google.com>
> Reviewed-by: Chris Blume <cblume@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#1491588}

Bug: 433723342
Change-Id: I81d9791e32c9ab224d42a940704e6a4ecd9bd708
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6784014
Reviewed-by: Chris Blume <cblume@chromium.org>
Commit-Queue: Devon Loehr <dloehr@google.com>
Cr-Commit-Position: refs/heads/main@{#1493497}
NOKEYCHECK=True
GitOrigin-RevId: d45fbf1f3800aafe5df814d5c428c2e0c7ea0098