file input click event breaks UI

I have a Trix editor sitting in a dialog modal. The dialog is configured to close when a user clicks outside of the dialog content. When a user clicks the "Attach Files" button in the Trix toolbar, my dialog closes.

[Looking at the Trix file input config](https://github.com/basecamp/trix/blob/main/src/trix/config/input.js#L23-L24), it appears that clicking "Attach Files" appends an `` to the DOM `` and then triggers a `click` on the input, thus causing my dialog to close.

If the `` were instead inserted as a sibling of the `` element my modal wouldn't break. Alternatively, if the Trix file input config could allow for changing where the `` element is inserted into the DOM that would provide a solution to my issue as well.

Start with src/trix/config/input.js lines 23-24, where the file input is appended and clicked. Trace how the Attach Files toolbar action uses this configuration, then determine whether the input should be placed beside the trix-editor element or expose a configurable insertion point. Done means the modal remains open when Attach Files is clicked and existing file attachment behavior still works.

Written by the indexing model from the issue text.