Change a few more directory strings to folder

Fixes <https://github.com/koreader/koreader/issues/7350>.

frontend/apps/filemanager/filemanagerbookinfo.lua

@@ -64,7 +64,7 @@ function BookInfo:show(file, book_props)
     table.insert(kv_pairs, { _("Format:"), filetype:upper() })
     table.insert(kv_pairs, { _("Size:"), size })
     table.insert(kv_pairs, { _("File date:"), os.date("%Y-%m-%d %H:%M:%S", file_modification) })
-    table.insert(kv_pairs, { _("Directory:"), BD.dirpath(filemanagerutil.abbreviate(directory)), separator = true })
+    table.insert(kv_pairs, { _("Folder:"), BD.dirpath(filemanagerutil.abbreviate(directory)), separator = true })
 
     -- book_props may be provided if caller already has them available
     -- but it may lack 'pages', that we may get from sidecar file

frontend/ui/widget/filechooser.lua

@@ -227,9 +227,9 @@ function FileChooser:genItemTableFromPath(path)
         if dir.name == ".." then
             text = up_folder_arrow
         elseif dir.name == "." then -- possible with show_current_dir_for_hold
-            text = _("Long-press to select current directory")
+            text = _("Long-press to select current folder")
         elseif dir.name == "./." then -- added as content of an unreadable directory
-            text = _("Current directory not readable. Some content may not be shown.")
+            text = _("Current folder not readable. Some content may not be shown.")
         else
             text = dir.name.."/"
             bidi_wrap_func = BD.directory