`wp_script_is( ..., 'enqueued' )` needs to check dependencies recursively - a single item's dependencies may only be a subset of the full dependency tree. Adds a new method on `WP_Dependencies` called `->recurse_deps()`. 

Adds unit test.

Props wonderboymusic, SergeyBiryukov, mikejolley.
Fixes #28404.

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