Add Datadog Serverless Azure Java Agent

[duncanpharvey]

What does this PR do?

• Adds a Java agent which starts the Datadog Serverless Mini Agent.
• Adds a Github workflow to build jar and add it to a new release when a tag with the format dd-serverless-azure-java-agent-* is pushed.
  • Also updates a Latest release which tracks the latest available release

Motivation

Start the Datadog Serverless Mini Agent in Azure Spring Apps by adding -javaagent:/path/to/dd-serverless-azure-java-agent.jar to JVM options.

https://datadoghq.atlassian.net/browse/SVLS-5078

Additional Notes

Relates to DataDog/libdatadog#547

• Datadog Serverless Mini Agent binary is packaged in jar
• In premain
  • Copy the Mini Agent binary from the jar to a temporary file and make it executable
  • Create a process with the Mini Agent binary
  • Start Mini Agent binary process

How to test the change?

See README

• Java 8 ✅
• Java 11 ✅
• Java 17 ✅
• Java 21 ✅

[jcstorms1]

I think this is fine, but I'd suggest being more explicit with the repo name. I think the current one is rather confusing. Perhaps something like dd-spring-apps-extension or dd-spring-apps-exporter. I don't think we need to mark it as serverless because we are the only team instrumenting here. We can add that to the description and mark us as owners.