feat: add sharing info to /workspaces endpoint (#21049)

closes: https://github.com/coder/internal/issues/858

Similar to https://github.com/coder/coder/pull/19375, this one uses
system permissions for fetching actual user and group data.

Modifies the `workspaces_expanded` view to fetch the required data; this way it's made available to all code paths that make use of it.  

Also fixes a bug in a test helper function that can result in `null` being saved to the DB for `user_acl` or `group_acl` and break tests; a defensive check constraint that prevents this is worth a PR, e.g:

`ALTER TABLE workspaces
   ADD CONSTRAINT group_acl_is_object CHECK (jsonb_typeof(group_acl) = 'object');`

Also adds missing  `OwnerName` in `ConvertWorkspaceRows`.

coderd/database/queries/workspaces.sql

@@ -451,6 +451,8 @@ WHERE
 		'', -- template_icon
 		'', -- template_description
 		'00000000-0000-0000-0000-000000000000'::uuid, -- task_id
+		'{}'::jsonb, -- group_acl_display_info
+		'{}'::jsonb, -- user_acl_display_info
 		-- Extra columns added to `filtered_workspaces`
 		'00000000-0000-0000-0000-000000000000'::uuid, -- template_version_id
 		'', -- template_version_name