Migrated build backend Setuptools to Hatch and add missing templates

[anushacs-dell]

Documentation & Community

• Added comprehensive CHANGELOG.md with semantic versioning history (v0.1.0 - v0.1.3)
• Created detailed CONTRIBUTING.md guide with development setup, workflow, and code standards
• Added CODE_OF_CONDUCT.md referencing OSGeo Code of Conduct
• Added GitHub issue templates: Bug Report and Feature Request
• Created pull request template with overview, checklist sections
• Added LICENSE

Build System & Tooling

• Migrated from setuptools to Hatch (pyproject.toml):
• Version is now dynamically sourced from zoo_runner_common/__about__.py
• Simplified dependencies management with environment-specific configurations
• Extended dependencies: added attrs, PyYAML, click, cwl-utils>=0.14

Updated GitHub Actions Workflow:

• Created .github/workflows/package.yaml for CI/CD pipeline
• Runs linting (ruff check, ruff format), tests across Python 3.10/3.11/3.12
• Automated PyPI publishing on tagged releases with Trusted Publishing
• Replaced older publish-pypi.yml workflow

Testing Infrastructure

• Added comprehensive test suite in tests/:
• test_base_runner.py: 18 unit tests covering BaseRunner functionality
• test_placeholder.py: Minimal placeholder test