Fixed destination file extension by mimeType in copyFolderTo()

[gee12]

Removed passing the mimeType to makeFile() for files when copying with DocumentFile.copyFolderTo(), which is why the extension of the copied files changed (because in system fileMimeTypeMap.java by this mimeType has no exact match with the extension, e.g. "text/html" corresponds to "htm", which led to copying the file "file.html " in "file.html.htm ").
With this change, the file extension and its name do not change, which is required.