Add DumpWithoutCrashing() for long paths in net::FillUnixAddress()

net::FillUnixAddress() currently allows unix domain socket address paths
to be used that are longer than will fit within `sockaddr_un::sun_path`,
as long as they fit within a sockaddr_storage. These are not guaranteed
to work when passed to platform APIs, so we should change that behavior.

This CL adds a DumpWithoutCrashing() when FillUnixAddress() creates an
address with a such an overly long path, to find if switching to
safer and correct behavior will break current consumers.

The longer path limit is 126 bytes on Linux, and 122 bytes on macOS,
while `sun_addr` is 108 bytes / 104 bytes, respectively, on those
platforms.

Bug: 416481248
Change-Id: Ice59565fa6e01f6a62b4c91d31cfe234bdee8f2b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6523265
Commit-Queue: mmenke <mmenke@chromium.org>
Reviewed-by: Adam Rice <ricea@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1458145}