expose "title" to item_append_files, item_rename_files, and other file related functions

[jordansread]

title is now a user editable field for individual files. The functionality to change or specify this field within sbtools was mentioned in #230 . This issue is to capture implementation details and decide on whether it is a priority for users.

Some questions that help with priority: Can we search for files based on title, or do other things with it? Right now we can find and replace files based on the file names, but we don't use title for that. Can an item have files w/ duplicate titles? I think it currently lets you have duplicate file names within an item.

[jordansread]

Looks like this would need to happen in multi_file_body

For giving it a title on initial upload.

[jordansread]

I was wrong about ☝️ multi_file, I think this needs to happen as two events - the file post and then the title update on the item. One snag to that is the need to verify which file is the one to update the title on.