Polish for global search ui

[jeremydw]

A few things can improve the global search experience:

1. For long results lists, the modal exceeds the vertical space on the screen and you can't scroll down to see more content, so content overflowing the viewport is inaccessible
2. It'd be nice to be able to deep link to the modal with a query pre-filled (e.g. to share search results with others). Maybe /cms/?modal=search&q=foo
3. Maybe we also have filter chips at the top that let you filter results by type (e.g. documents, translations, releases, etc.)

Screenshot: