Add demo for JEP 345 - NUMA-Aware Memory Allocation for G1

[Abhineshhh]

close : #326

This PR implements a comprehensive informational demo for Java 14 feature JEP 345 - NUMA-Aware Memory Allocation for G1.

Changes

• Created NumaAwareG1Demo.java in java14/jep345/
• Added JEP 345 entry to JDK14Info.json with proper metadata
• Registered demo in Java14DemoLoader.java (ordered by JEP number)

Demo Content

The demo provides detailed information about:

• NUMA (Non-Uniform Memory Access) architecture
• G1 GC improvements in Java 14 for NUMA systems
• JVM flags to enable NUMA-aware allocation (-XX:+UseG1GC -XX:+UseNUMA)
• Performance benefits on multi-socket machines (10-30% improvement for large heaps)
• When and how to use this feature
• Monitoring and verification methods with tools like numastat
• Practical examples and commands

Key Features

1. Detailed explanation of NUMA architecture and memory locality
2. Before/After comparison showing G1 GC behavior changes
3. JVM configuration examples with proper flags
4. Performance considerations for different heap sizes
5. OS-level integration examples (Linux numactl, Windows NUMA API)
6. Debugging and monitoring tips using JVM logs

This is an informational demo as NUMA awareness is a JVM-level optimization that requires no code changes - only JVM flag configuration.

[AloisSeckar]

Hi @Abhineshhh and thanks for new contribution. Just a two nitpicks to solve from me.