PHPUnit test and Coverage

• Feat: Issue #133 Resolved minor bugs and improved code stability.
• Feat: Add PHPUnit unit/feature/exception tests, including console command coverage.
• Feat: Add Testbench workbench scaffolding.
• Feat: PHPUnit configuration to run package tests and Coverage using GitHub Actions.
• Refactor: Cognito client traits into dedicated Manage Action traits.
• Doc: Update related docs and CI configs.