Add an ability to toggle visibility of any field

[versusbassz]

The possible implemention:

• count values lengths on the backend and add a prop to the field, sort of toggle: true
• if the field is true add +/- toggle button (pos:a, r0, t0, visible on hover) to a related value
• the field has to be closed by default, a fixed part of the field has to be visible in this state (with gradient)

[versusbassz]

I don't remember for now what was the idea, unfortunately. Maybe, I'll reproduce an issue in the future during development.

[versusbassz]

I think, it was about huge serialized values, e.g.: wp_yoast_notifications. post_content is a about the same problem, I think.
Sometimes, you just want to hide them or decrease their height like in ACF repeaters.

Raw value:

Pretty value:

[versusbassz]

Done.

In fact, it's a "Spoiler" functionality.
The decision about to apply a spoiler to a value or not to apply is made in javascript logic (enabled prop of Spoiler component).