OpenSearch 2.x Fixtures

New

• Create OpenSearch 2.x data fixtures, providing the same set of functionalities as in the Elasticsearch fixtures:
  • File fixtures
  • Directory Loader fixtures:
    • Array Directory fixtures
    • Json Directory fixtures
  • Adapter
  • Executor
  • Purger

Other changes

• Add tests to the new type
• Add documentation
• Add code quality tools in the library (Rector and PHPStan)
• Run those tools in the CI pipeline
• Replace deprecated SonarCloud action with latest SonarQube Scan action to perform Sonar checks