[Seven] - Form generator

[sneridagh]

Important

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A form generator with a performant library to build forms from JSON-schema definitions.
This is not related to the "main" content form, which is a complete different beast.
It's for the most simple form rendering use cases.
It should be able to catch the widgets from a default set of pre-defined and registered widgets for public forms, or specify your own registered ones (useful for theming forms with a complete different set of widgets too).

Link to the parent PLIP

#6665