Summary: Phorge's search calls all/any objects (tasks, changesets, mockups, commits, users) "documents". The object types in {Diviner|Legalpad|Phriction} are also called documents. Also note that the "Document Engine" stuff in PhabricatorSystemSelectViewAsController refers to viewing files in Diffusion (as Jupyter Notebook, as Source) which isn't changed by this patch. When referring to all and any kind of object types, use the term "item" instead to decrease ambiguity. This change only covers search UI strings exposed to end users. Closes T16131 Test Plan: * `grep -r " Document" .` and `grep -r " document" .` (good luck) * Go to http://phorge.localhost/search/, check for "Open Documents" in the sidebar * Go to http://phorge.localhost/search/query/advanced/, check for the "Document Status" checkboxes fields, check for "Document Types" search field, click its Browse button, check the dialog for "Browse Document Types" and "Select a document type" Reviewers: O1 Blessed Committers, mainframe98 Reviewed By: O1 Blessed Committers, mainframe98 Subscribers: amybones, tobiaswiese, valerio.bozzolan, Matthew, Cigaryno Maniphest Tasks: T16131 Differential Revision: https://we.phorge.it/D26114