Drop the redundant account pill from /write; the app bar carries identity
When signed in, the editor showed two identical identity pills: WriteStudio's
own AccountPill in the actions bar and the app bar's app-bar__identity (which
already provides the profile link, the Publications nav, and Sign out). Remove
WriteStudio's pill — and the now-unused AccountPill component, its test, and
its CSS — leaving the actions bar with just the Publish button.