Add script to analyze core dumps with gdb (#10)

Introduces analyze_core_dumps.sh to automate core dump analysis using GDB.
The script provides stack traces and register information for analyzing
crashes in executables, with particular focus on Postgres/Cloudberry.

Features:
- Automatic core dump detection and analysis
- Detailed stack traces and register info via GDB
- Comprehensive logging of analysis results
- Dependency checking for required tools
- Clear return codes for automation:
 0: No cores found
 1: Cores processed successfully
 2: Errors (missing deps or processing failures)

The script is designed to integrate with automated testing and CI/CD
pipelines while also being useful for manual debugging sessions.

Add conditional debug build support to configure

Modifies configure script to optionally enable debug-related compile options:
 - --enable-debug
 - --enable-profiling
 - --enable-cassert
 - --enable-debug-extensions

These flags are enabled when ENABLE_DEBUG=true is set in the environment.
This provides flexibility to generate both debug and non-debug builds from
the same script, defaulting to non-debug builds.