Cross-reference `WP_Comment_Query::query()` as the location for finding information on default arguments for `WP_Comment_Query`.

Also updates the return types on `get_comments()` and `get_approved_comments()`, as an integer can also be returned if the `$count` argument is true.

Fixes #30111.

Built from https://develop.svn.wordpress.org/trunk@30281


git-svn-id: http://core.svn.wordpress.org/trunk@30281 1a063a9b-81f0-0310-95a4-ce76da25c4cd