Attributes not settable on Fieldsets

[KDederichs]

Describe the bug You can not set attributes on Fieldsets (neither in detail nor in edit/new)

To Reproduce FormField::addFieldset('Foo')->setFormTypeOptions(['attr' => ['data-controller' => 'price-calculator']]),

will not render the attribute to the fieldset tag

(OPTIONAL) Additional context It works for tabs, so it's a bit inconsistent

[lguigo22]

and setHtmlAttributes too. not practical to show/hide areas dynamically