docs: expand profiling guide with JVM and async-profiler coverage

[andygrove]

Summary

Add detailed profiling guide - rendered version

Changes

• Renames profiling_native_code.md to profiling.md and expands it into a comprehensive profiling guide
• Adds a tool comparison table (async-profiler vs JFR vs cargo-flamegraph) with guidance on when to use each
• Adds async-profiler section: installation, attaching to running Spark apps via asprof, java agent usage, event types, output formats, platform notes
• Adds Java Flight Recorder section: spark-submit flags, jcmd dynamic recording, viewer options, useful JFR events for Comet debugging
• Adds Tips for Profiling Comet section: wall-clock profiling for JNI overhead, alloc profiling around Arrow FFI, isolating Rust issues, correlating JVM/native frames
• Preserves all existing cargo bench / cargo-flamegraph content
• Links to benchmarks/tpc/README.md for integrated benchmark profiling

[comphead]

Thanks @andygrove we might want to include a full working example

For example I use

TPCH Local Q4 (Profiler)
JAVA_HOME=/opt/homebrew/opt/openjdk@17/libexec/openjdk.jdk/Contents/Home SPARK_HOME=/opt/homebrew/Cellar/apache-spark/3.5.5/libexec spark-submit --master="local[*]" --conf spark.driver.memory=8G --conf spark.executor.instances=1 --conf spark.executor.cores=4 --conf spark.cores.max=4 --conf spark.executor.memory=16g --conf spark.memory.offHeap.enabled=true --conf spark.memory.offHeap.size=16g --conf spark.comet.explainFallback.enabled=true --conf spark.comet.logFallbackReasons.enabled=true --conf spark.eventLog.enabled=true --jars $COMET_JAR --driver-class-path $COMET_JAR --conf spark.driver.extraClassPath=$COMET_JAR --conf spark.executor.extraClassPath=$COMET_JAR --conf spark.plugins=org.apache.spark.CometPlugin --conf spark.shuffle.manager=org.apache.spark.sql.comet.execution.shuffle.CometShuffleManager --conf spark.comet.enabled=true --conf spark.comet.exec.shuffle.enableFastEncoding=true --conf spark.comet.exec.shuffle.fallbackToColumnar=true --conf spark.comet.exec.replaceSortMergeJoin=true --conf spark.comet.cast.allowIncompatible=true --conf spark.comet.scan.impl=native_iceberg_compat --conf "spark.executor.extraJavaOptions=-agentpath:/Users/xxx/Downloads/async-profiler-4.3-macos/lib/libasyncProfiler.dylib=start,event=cpu,file=profile-executor.html,tree" --conf "spark.driver.extraJavaOptions=-agentpath:/Users/xxx/Downloads/async-profiler-4.3-macos/lib/libasyncProfiler.dylib=start,event=cpu,file=profile-driver.html,tree" dev/benchmarks/tpcbench.py --name comet --benchmark tpch --data ../datafusion-benchmarks/tpch/data --queries ../datafusion-benchmarks/tpch/queries --output . --iterations 1 --query 4

And this flag helps a bit file=profile-driver.html,tree which builds an output as a tree hierarchy

[martin-g]

Suggested change

	the `--async-profiler` flag. See [benchmarks/tpc/README.md](../../benchmarks/tpc/README.md)
	the `--async-profiler` flag. See [benchmarks/tpc/README.md](../../../benchmarks/tpc/README.md)

[martin-g]

Suggested change

	runs. See [benchmarks/tpc/README.md](../../benchmarks/tpc/README.md) for details.
	runs. See [benchmarks/tpc/README.md](../../../benchmarks/tpc/README.md) for details.

[martin-g]

Suggested change

	wget https://github.com/async-profiler/async-profiler/releases/download/v3.0/async-profiler-3.0-linux-x64.tar.gz
	wget https://github.com/async-profiler/async-profiler/releases/download/v3.0/async-profiler-3.0-linux-x64.tar.gz
	mkdir -p /opt/async-profiler

[martin-g]

Also, /opt usually requires sudo privileges. Maybe use $HOME/opt/... ?!

[martin-g]

Suggested change

	These benchmarks are useful when for comparing performance between releases or between feature branches and the
	These benchmarks are useful for comparing performance between releases or between feature branches and the