Add comprehensive documentation explaining code quality improvements and refactoring patterns

[Copilot]

This PR adds detailed documentation explaining the systematic code quality improvements that have been implemented across multiple versions of the Microsoft SQL Server JDBC driver. The documentation provides valuable context for understanding the evolution of the codebase and serves as a reference for future development.

What's Added

Three comprehensive documentation files:

📚 CODE_IMPROVEMENTS_EXPLAINED.md

A complete overview categorizing all major code quality improvements:

• Modern Java Language Features: Diamond operator usage, enhanced for-each loops, StandardCharsets adoption
• Code Simplification: Boolean expression simplification, unnecessary return statement removal
• Performance Optimizations: System.arraycopy() usage, type enumeration patterns
• Standards Compliance: Constants vs literals, import organization, resource management
• Maintenance Improvements: Test infrastructure modernization, dependency management

🔧 TECHNICAL_IMPROVEMENTS_EXAMPLES.md

Technical deep-dive with actual code examples from the repository:

• Abstract class design patterns from dtv.java showing the DTVExecuteOp pattern
• Parameter handling improvements from Parameter.java demonstrating Unicode configuration
• Type safety enhancements from DataTypes.java showing the JavaType enumeration
• Resource management patterns and serialization proxy examples
• Coding standards compliance with before/after code comparisons

📋 README_CODE_IMPROVEMENTS.md

Executive summary with quick reference tables showing:

• Impact summary of each improvement type
• Historical context across versions 6.1.x through 9.4.x+
• Alignment with established coding guidelines
• Guidance for future development

Why This Matters

The CHANGELOG.md shows a pattern of systematic code quality improvements over many releases, but the reasoning and benefits weren't documented comprehensively. This documentation:

1. Explains the "why" behind changes like "Replaced explicit types with <> (the diamond operator)"
2. Provides concrete examples showing before/after code patterns
3. Documents performance benefits of changes like StandardCharsets usage
4. Serves as a reference for code reviews and new development
5. Preserves institutional knowledge about the codebase evolution

Examples of Improvements Documented

Diamond Operator Usage:

// Before: Verbose and redundant
List<String> names = new ArrayList<String>();

// After: Clean and modern
List<String> names = new ArrayList<>();

Boolean Expression Simplification:

// Before: Overly complex
if (active == true) { ... }
if (condition == false) { ... }

// After: Natural language flow
if (active) { ... }
if (!condition) { ... }

StandardCharsets for Performance:

// Before: Can throw UnsupportedEncodingException
byte[] bytes = text.getBytes("UTF-8");

// After: Compile-time safe and efficient
byte[] bytes = text.getBytes(StandardCharsets.UTF_8);

This documentation helps developers understand the thoughtful evolution of the codebase and provides patterns to follow for maintaining high code quality standards.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• sqlclientdrivers.pkgs.visualstudio.com
  • Triggering command: /usr/lib/jvm/temurin-17-jdk-amd64/bin/java --enable-native-access=ALL-UNNAMED -classpath /usr/share/apache-maven-3.9.11/boot/plexus-classworlds-2.9.0.jar -Dclassworlds.conf=/usr/share/apache-maven-3.9.11/bin/m2.conf -Dmaven.home=/usr/share/apache-maven-3.9.11 -Dlibrary.jansi.path=/usr/share/apache-maven-3.9.11/lib/jansi-native -Dmaven.multiModuleProjectDirectory=/home/REDACTED/work/mssql-jdbc/mssql-jdbc org.codehaus.plexus.classworlds.launcher.Launcher compile -q (dns block)

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