Fix SRF "gallery format" overlay and redirect

[freephile]

MediaWiki's evolution of its gallery HTML structure forces SRF to adapt.

MediaWiki has adopted a "mw-file-description" HTML class as more semantic and specific for file description links in gallery displays. It replaces the former, generic, "image" class applied to the same elements.

So, Semantic Result Formats - Gallery output needs to adapt specifically in its "overlay" and "redirect" options because they relied upon the old HTML output of MediaWiki.

• modifies the JavaScript files for overlay and redirect
• Adds QUnit tests for overlay and redirect with assertions about the HTML
• Fixup to the 'fancybox' jQuery module (without upgrading)

If running this in a containerized / development environment, you can test only gallery-related functionality "cd /var/www/html/extensions/SemanticResultFormats && composer phpunit -- --filter Gallery"

Fixes Issue #940 with explanation by @ADB-Linux

[codecov[bot]]

Codecov Report

:white_check_mark: All modified and coverable lines are covered by tests. :white_check_mark: Project coverage is 46.24%. Comparing base (b2b04d9) to head (d9c5fe5).

Additional details and impacted files

@@            Coverage Diff            @@
##             master     #977   +/-   ##
=========================================
  Coverage     46.24%   46.24%           
  Complexity     2361     2361           
=========================================
  Files            80       80           
  Lines          8957     8957           
=========================================
  Hits           4142     4142           
  Misses         4815     4815           

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