Adding UdpExporter for Otlp spans

[srprash]

Description of changes:

Adding a new SpanExporter that can export spans to a configurable endpoint over UDP.

• The spans are first protobuf encoded, then base64 encoded, then prefixed with T1S or T1U (depending on sampled), and finally appended to the {"format":"json","version":1}\n string before being exported to the endpoint, default is 127.0.0.1:2000.
• Related: Add OTLP UDP exporter aws-otel-python-instrumentation#232

Testing:

Wrote a test to create and export a real span via X-Ray Daemon running locally.

• Unit test

  @Test
  public void testExporter() { // TODO: only for testing. remove.
  Tracer tracer = OpenTelemetrySdk.builder().build().getTracer("hello");
  
  Span mySpan = tracer.spanBuilder("DoTheLoop_5").startSpan();
  int numIterations = 5;
  mySpan.setAttribute("NumIterations", numIterations);
  mySpan.setAttribute(AttributeKey.stringArrayKey("foo"), Arrays.asList("bar1", "bar2"));
  try (var scope = mySpan.makeCurrent()) {
    for (int i = 1; i <= numIterations; i++) {
      System.out.println("i = " + i);
    }
  } finally {
    mySpan.end();
  }
  
  OtlpUdpSpanExporter exporter = new OtlpUdpSpanExporterBuilder().build();
  
  ReadableSpan readableSpan = (ReadableSpan) mySpan;
  SpanData spanData = readableSpan.toSpanData();
  
  exporter.export(Collections.singletonList(spanData));
  }

• Observed trace data in X-Ray service

  {
  "Id": "1-246f2975-8c1d813535803fea548be818",
  "Duration": 0.003,
  "LimitExceeded": false,
  "Segments": [
     {
         "Id": "455654be8f47d669",
         "Document": {
             "id": "455654be8f47d669",
             "name": "DoTheLoop_5",
             "start_time": 1730828092.934588,
             "trace_id": "1-246f2975-8c1d813535803fea548be818",
             "end_time": 1730828092.9371202,
             "annotations": {
                 "span.name": "DoTheLoop_5",
                 "span.kind": "INTERNAL"
             },
             "metadata": {
                 "telemetry.sdk.language": "java",
                 "service.name": "unknown_service:java",
                 "foo": [
                     "bar1",
                     "bar2"
                 ],
                 "NumIterations": 5,
                 "telemetry.sdk.version": "1.34.1",
                 "telemetry.sdk.name": "opentelemetry"
             }
         }
     }
  ]
  }

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[srprash]

The trivy image scan failure causing CI to fail is due to this issue: aquasecurity/trivy-action#389
No fix from trivy yet. A suggested workaround is to pull the db image from AWS ECR but I haven't tried it.

[srprash]

Had to override the checks and merge due to trivy scan issue mentioned above.