Sort files

[alexweininger]

We should add a feature that allows you to sort the files within the category. The files can be sorted by:

• Name (alphabetically)
• Pinned *this would depend on our strategy for pinning files - like adding a separate tab or not
• Recently added
• Recently opened

This page shows how we can implement a simple select for the sorting. https://material-ui.com/components/selects/#controlled-open-select

The drop down can be added in a new section under the search bar on the right.