Provide widgets IDs to Operation::container

[nicksenger]

Use of operation::scoped requires a widget which provides its ID to Operation::container. Currently none of the provided container widgets do this, so using scoped operations requires implementation of a custom widget. This PR adds the option to provide an ID to each container widget that doesn't have it already (button, container, row, column, pane grid) and provides this ID to Operation::container in Widget::operate.

[hecrj]

I wonder if we could just get away with adding the id to just the Container widget?

[tarkah]

I wonder if we could just get away with adding the id to just the Container widget?

I agree with this. Wrap whatever with a Container if you need to use scoped

[nicksenger]

Sounds good, I cut this down to just the container 👍

[hecrj]

Great! I have rebased and dropped 63cfec6, since Scrollable already has an Id and it makes sense to provide it.