Fixes #10019. When bulk editing subfields, such as a field within a group, changes are not actually made because field paths are incorrect. This is because when opening the bulk edit drawer, fields are flattened into options for the field selector, but then remain flattened when thread into RenderFields. Once received, RenderFields attempts to build up its own field paths, but are never correct because they must did not pass through their parent's field in order to gain its "parent" path. The fix is to separate the reduce logic for the field selector from the fields to render, this way the fields sent to RenderFields can be traversed as expected.