Correct the `@param` docs for arguments that are truthy/falsey.

See #30799.

Built from https://develop.svn.wordpress.org/trunk@30983


git-svn-id: http://core.svn.wordpress.org/trunk@30969 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Comment List Tables:

* Declare `$extra_items` property
* Since `->get_column_info()` overrides its parent's method, it doesn't need to set `_column_headers`, which is an undeclared property that is only used for caching the lookup after the first run in the parent class, which isn't called in the child class.
* `$_args` in `WP_List_Table` has to be `protected` for `WP_Post_Comments_List_Table` to legally access it. `$_args` is awkward as is and should probably be only available via a getter.

See #30799.

Built from https://develop.svn.wordpress.org/trunk@30984


git-svn-id: http://core.svn.wordpress.org/trunk@30970 1a063a9b-81f0-0310-95a4-ce76da25c4cd