[Tagging] Inclusive Counts on Taxonomy Detail Page

[bradenmacdonald]

"As a user viewing a taxonomy in Studio, I want a more efficient experience."

Design: "Taxonomy Detail Page" in Figma "Content Tagging MVP"

Update the API (and if needed, the UI) so that the counts shown include the total number of grandchild tags, not just the number of direct children. See Figma for an example.