socket.send_fds() flags and address parameters have no effect

[mbachry]

Bug report

Bug description:

socket.send_fds accepts flags and address parameters, but they aren't passed down to socket.sendmsg.

CPython versions tested on:

3.13

Operating systems tested on:

Linux

Linked PRs

• gh-127840: pass flags and address from send_fds #127841
• [3.14] gh-127840: pass flags and address from send_fds (GH-127841) #134474
• [3.13] gh-127840: pass flags and address from send_fds (GH-127841) #134475
• gh-127840: Revert "gh-127840: pass flags and address from send_fds (GH-127841)" #134482

[gpshead]

the original PR was reverted due to an issue on the cpython test suite side. it had passed our CI many months ago. i didn't hit Update on it before finally merging; if I had, it'd have failed as the buildbots and backport PRs such as #134474 did. easy to fix as noted in #127841 (comment)