Using named argument "array" on "set" filter throws exception

Problem/Motivation

With the release of 8.x-2.3, we renamed the old "set" filter to "recursive_merge". If anyone was using the named argument, "array" on the "set" filter, 8.x-2.3 would cause it to throw an exception since the new "set" filter was looking for a "path" argument".

Probably no one was using this since the named arguments were undocumented.

Proposed resolution

This will be fixed as part of #3209575: Rename the named argument of Twig filters from "path" to "at"