This introduces the singular `edit_term`, `delete_term`, and `assign_term` meta capabilities for terms, and switches the base capability name for tags from `manage_categories` to `manage_post_tags` and the corresponding `edit_post_tags`, `delete_post_tags`, and `assign_post_tags`.
All of these capabilities ultimately map to `manage_categories` so by default there is no change in the behaviour of the capabilities for categories, tags, or custom taxonomies. The `map_meta_cap` filter and the `capabilities` argument when registering a taxonomy now allow for control over editing, deleting, and assigning individual terms, as well as a separation of capabilities for tags from those of categories.
Fixes#35614
Props johnjamesjacoby for feedback
git-svn-id: https://develop.svn.wordpress.org/trunk@38698 602fd350-edb4-49c9-b593-d223f7449a82