Issue #3209440 by JohnAlbin: Twig "set" filter does not replace target array

src/Template/TwigExtension.php

...twig_extension_test/components_twig_extension_test.module

...ents-twig-extension-test-recursive-merge-filter.html.twig

...lates/components-twig-extension-test-set-filter.html.twig

tests/src/Kernel/TwigExtensionTest.php

tests/src/Unit/TwigExtensionFiltersTest.php