Add code requirements for using the Interactivity API on any block

[juanmaguitar]

The following requirements should be added to Requirements of the Interactivity API

• Add "supports": { "interactivity": true } to block.json
• Add the data-wp-interactive directive to the main DOM element
  • To indicate to the Interactivity API "engine" to hydrate this dom element and its children

These requirements are already covered when creating an interactive block using @wordpress/create-block-interactive-template but they should be added to the docs for blocks not created with this template that want to start using the Interactivity API.

cc: @luisherranz

[juanmaguitar]

Closing issue as per #53342 & #53362