Fix: Add epoll native transport for linux-aarch_64

[BulkBeing]

Problem

When running Numaflow UDF containers aarch64 platforms, the container crashes on startup with:

  DEBUG io.netty.channel.epoll.Epoll -- Epoll support is not available: could not load a native library: netty_transport_native_epoll_aarch_64
  Exception in thread "main" java.lang.UnsatisfiedLinkError: failed to load the required native library
          at io.netty.channel.epoll.Epoll.ensureAvailability(Epoll.java:90)
          at io.netty.channel.epoll.EpollIoHandler.<clinit>(EpollIoHandler.java:62)
          at io.netty.channel.epoll.EpollEventLoopGroup.<init>(EpollEventLoopGroup.java:123)
          at io.netty.channel.epoll.EpollEventLoopGroup.<init>(EpollEventLoopGroup.java:110)
          at io.netty.channel.epoll.EpollEventLoopGroup.<init>(EpollEventLoopGroup.java:87)
          at io.numaproj.numaflow.shared.GrpcServerUtils.createEventLoopGroup(GrpcServerUtils.java:63)
          at io.numaproj.numaflow.shared.GrpcServerWrapper.createServer(GrpcServerWrapper.java:166)
          at io.numaproj.numaflow.shared.GrpcServerWrapper.<init>(GrpcServerWrapper.java:40)
          at io.numaproj.numaflow.sinker.Server.<init>(Server.java:46)
          at io.numaproj.numaflow.sinker.Server.<init>(Server.java:33)

Root Cause

GrpcServerUtils.createEventLoopGroup() falls through to new EpollEventLoopGroup() on any non-macOS platform. This requires the Netty epoll JNI native library (.so) to be on the classpath. The SDK ships netty-transport-native-epoll with the linux-x86_64 classifier but not linux-aarch_64.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
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Additional details and impacted files

@@           Coverage Diff           @@
##             main     #214   +/-   ##
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  Coverage        ?   60.79%           
  Complexity      ?      561           
=======================================
  Files           ?      155           
  Lines           ?     3584           
  Branches        ?      254           
=======================================
  Hits            ?     2179           
  Misses          ?     1225           
  Partials        ?      180           

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