This changes the global `$wp_taxonomies` to an array of `WP_Taxonomy ` objects. `WP_Taxonomy ` includes methods to handle rewrite rules and hooks.
Each taxonomy argument becomes a property of `WP_Taxonomy`. Introducing such a class makes further improvements in the future much more feasible.
Props boonebgorges for review.
Fixes#36224. See #36217.
git-svn-id: https://develop.svn.wordpress.org/trunk@38747 602fd350-edb4-49c9-b593-d223f7449a82