fix: allow converting a file to directory and vice-versa (#117)

If you rename a file to have a `/` at the end, oil will detect the
change as a delete + new directory. Similarly, if you delete the
trailing `/` from a directory, it will delete the dir and create a new
file. This should help with the case where you want to create a new file
but forgot to add the trailing `/` and now you have a file instead.

lua/oil/mutator/parser.lua

@@ -207,6 +207,12 @@ M.parse = function(bufnr)
             entry_type = "link",
             link = parsed_entry.link_target,
           })
+        elseif entry[FIELD_TYPE] ~= parsed_entry._type then
+          table.insert(diffs, {
+            type = "new",
+            name = parsed_entry.name,
+            entry_type = parsed_entry._type,
+          })
         else
           original_entries[parsed_entry.name] = nil
         end