Create a toggle component

[IreneStr]

This toggle component will be used to mark cornerstone content in the sidebar, but probably also in other places later. Therefore, make it flexible. Use backported Gutenberg components when possible.

Context of the toggle:

[afercia]

There's a (slightly) long debate about these switch toggles going on in Gutenberg, see WordPress/gutenberg#2146

Regardless of what will happen there, if we really want to use these kind of UI I'd strongly recommend to implement it in a way that there's always a clear textual indication of the switch state.

Worth reminding the MyYoast toggles do use a visible hint "On/Off" to give some visual feedback about the switch state:

There are also different options to give the same visual feedback:

• material.io suggests to use the visible inline label (if any):

• Gutenberg provides a description below the inline label that could be used for this purpose:

[omarreiss]

So we decided to go with MyYoast toggles.