10.2.0 compatibility

WIP - update mercury-dialog npm packages; send ajaxPageState to parent window on initial load; add middleware class to decompress ajax_preview_page_state request param

Closes #3411974

added 2 commits

• 05452621 - Moved symm/asymm test setup into drush. Improved cypress tests. Removed outdated src folder.
• e984a5b6 - Ignore uncaught exceptions.

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added 1 commit

• ae1d9f57 - Git ignore screenshots

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merged