Instance page breadcrumb needs a dropdown selector

[charliepark]

When on an instance page, you should be able to select other instances from that project.

[benjaminleonard]

Some kind of integrated combobox is probably useful, we'll also want some way to get back to the list page.

Have discussed that we probably need to consider the breadcrumbs a little more, it might be the visual treatment, but often people do not realise they are breadcrumbs at all.

[paryhin]

I have some initial ideas in this file: https://www.figma.com/design/zlhgBnPivrzeJ3wpIOI5Om/Navigation?node-id=2016-35341&t=6agQxTcMEOBXsXlx-1

[charliepark]

Definitely interested in exploring some of those ideas. In order to get the dropdown into v10, I have #2392, and we can absolutely build on that with a more robust breadcrumb solution.