Properly handle non-managed networking

[mcm001]

Description

The previous code did not handle various null cases, but more importantly, the non-managed device codepath was totally bjork if the server was not at localhost. This code path is only taken if networking is disabled, and I wasnt able to find any testing outside of localhost:

[19:34:04] [2026-04-24 19:34:05] [General - NetworkUtils] [ERROR] java.lang.NullPointerException: Cannot invoke "java.net.NetworkInterface.getHardwareAddress()" because the return value of "java.net.NetworkInterface.getByInetAddress(java.net.InetAddress)" is null
    at org.photonvision.common.networking.NetworkUtils.getMacAddress(NetworkUtils.java:270)
    at org.photonvision.common.dataflow.networktables.NetworkTablesManager.checkHostnameAndCameraNames(NetworkTablesManager.java:249)
    at org.photonvision.common.util.TimedTaskManager$CaughtScheduledThreadPoolExecutor.lambda$wrap$0(TimedTaskManager.java:56)
    at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:545)
    at java.base/java.util.concurrent.FutureTask.runAndReset(FutureTask.java:369)
    at java.base/java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:310)
    at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1090)
    at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:614)
    at java.base/java.lang.Thread.run(Thread.java:1474)

Changes

• Open/connect a UDP socket to query local address
• Handle more error cases, weird network interfaces more cleanly

Meta

Merge checklist:

• Pull Request title is short, imperative summary of proposed changes
• The description documents the what and why, including events that led to this PR
• If this PR changes behavior or adds a feature, user documentation is updated
• If this PR touches photon-serde, all messages have been regenerated and hashes have not changed unexpectedly
• If this PR touches configuration, this is backwards compatible with all settings going back to the previous seasons's last release (seasons end after champs ends)
• If this PR touches pipeline settings or anything related to data exchange, the frontend typing is updated
• If this PR addresses a bug, a regression test for it is added
• If this PR adds a dependency, the license has been checked for compatibility and steps taken to follow it

[mcm001]

Another option is wpilibsuite/allwpilib#8828