This fixes an issue where fields with the name `file` was being
serialized as a top-level field in multipart form data even when the
collection was not upload-enabled. This caused the value of `file` (when
used as a regular field like a text, array, etc.) to be stripped from
the `_payload`.
- Updated `createFormData` to only delete `data.file` and serialize it
at the top level if `docConfig.upload` is defined.
- This prevents unintended loss of `file` field values for non-upload
collections.
The `file` field now remains safely nested in `_payload` unless it's
part of an upload-enabled collection.
112e081d8f
