Supporting single `tabpanel`

I am working on a project picker component that is using tabs for switching between lists of projects. Since the content type for each tab is the same, only the source changes, I wish to use single `tabpanel` with a `virtualised-list` inside.

```html

```

After talking to @keithamus I have learned that currently `tab-container` requires to have the same set of tabpanels as tabs as it announces panel changes to the screen reader.

Is that feasible to support mentioned use case and comply with accessibility requirements set on the `tab-container-element`?

Start by reviewing the tab-container-element behavior described in the issue and the provided tab, tabpanel, and virtualised-list markup. Determine whether a single panel can support changing tab content while preserving the component's screen-reader announcements; done means the requested project-picker pattern is supported and remains accessible.

Scritto dal modello di indicizzazione a partire dal testo della issue.