Re-add the topIcons GNOME Shell extension

Thanks to doing #16608 (closed) in 3.13.2, we’ll have a chance to revert this change quickly, in 3.14, if we’ve collected enough data to conclude that the uproar is too severe.

Feature Branch: bugfix/16709-enable-topicons

Parent Task: #8309

Related issues

Related to #16608 (closed)
Blocks #8310
Blocks #16209

Original created by @intrigeri on 16709 (Redmine)

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