Add logo for Project Browser / Drupal.org

If you create a logo.png in the root of your project on the default branch, you can display a logo in the Project Browser and on Drupal.org.

We discussed this in Project Browser issue https://www.drupal.org/project/project_browser/issues/3396267 and suggest the following logo: https://www.drupal.org/files/issues/2024-07-17/Environment_Indicator_t-f...