WIP: Try gradle wrapper

[rokon12]

NOTE: This is still a work in progress and needs extensive testing across all supported configurations.

This PR adds comprehensive Gradle build system support to the Jakarta EE starter archetype, allowing users to generate projects with either Maven (default) or Gradle build systems.

Changes Made

• Added buildSystem parameter to archetype metadata with validation for maven (default) and gradle options
• Created Gradle build templates with full Jakarta EE dependency management and runtime plugin configurations
• Added Gradle wrapper files (gradlew, gradlew.cmd, gradle-wrapper.jar, gradle-wrapper.properties)
• Enhanced post-generation script to conditionally remove Maven/Gradle files based on chosen build system

📖 Documentation Updates

• Updated main README.md with Gradle build system usage examples
• Enhanced archetype README.md with build system parameter documentation
• Modified generated project README template to provide build-system-specific instructions

Usage Examples

Generate Maven project (default):
mvn archetype:generate -DarchetypeGroupId="org.eclipse.starter" -DarchetypeArtifactId="jakarta-starter"
Generate Gradle project:
mvn archetype:generate -DarchetypeGroupId="org.eclipse.starter" -DarchetypeArtifactId="jakarta-starter" -DbuildSystem=gradle

Known Issues / TODO

• Need comprehensive runtime plugin testing
• Docker integration may need adjustments for Gradle
• Some runtime-specific Gradle configurations may need refinement
• Validation of all generated Gradle plugin configurations

[eclipse-starter-bot]

Can one of the admins verify this patch?