Disable popout feature for widgets using the Widget API

[skolmer]

Is your suggestion related to a problem? Please describe.

Users can currently popout widgets that are using the Widget API. This should be prevented if a widget initialized the Widget API.

Describe the solution you'd like

If a widget calls the start() function of the Widget API disable the popout feature of the widget container.

[t3chguy]

The pop out feature is likely going away in favour of a full-screen view interaction.

Related #15321

[turt2live]

While we wait for fullscreen interactions or better popout requirements, we could implement an io.element.no_popout capability that gets auto-approved and respected by Element.

[skolmer]

While we wait for fullscreen interactions or better popout requirements, we could implement an io.element.no_popout capability that gets auto-approved and respected by Element.

Because popout widgets are not supported by the widget-api yet shouldn't the button be disabled by default when the widget-api is used?

[turt2live]

Some widgets use the widget API for added functionality but don't require it, like the built-in Jitsi widget. We'd want to keep popout for these widgets but not others