TASK: Check if container extension is installed

[extcode]

Related: #7

[what-the-diff]

PR Summary

• Addition of Utility Class
  The Rootline.php file was updated with a new utility class ExtensionManagementUtility from TYPO3\CMS\Core\Utility. This enhancement should optimize code functionality.

• Creating New Configuration Files
  Six new TypoScript and TSconfig configuration files have been added into the Tests/Fixtures/base_example/Configuration directory. These configurations relate to content elements like images, extensions like responsive images, rendering, backend layouts, and general setup. All these files are crucial for extending functionalities and user interface improvements within the app.

• Inclusion of Resources and Templates
  Two files were introduced in the Tests/Fixtures/base_example/Resources/Private directory under Partials/FluidStyledContent/Media and Templates/FluidStyledContent. They're HTML files dealing with image content. They likely service as templates for rendering image-related content.

• Test Fixtures and Base Test
  0colDatabase.php and BaseTest.php files were added under Tests/Fixtures/base_example/Test/Fixtures and Tests/Functional directories respectively. The 0colDatabase.php file helps test the application's database-related functionalities while the BaseTest.php provides a foundational test setup for the app.

• Package Dependencies
  A new composer.json file has been included in the Tests/Fixtures/base_example directory. This is fundamental for documenting and managing dependencies (external code libraries) needed by the application.