Block editor: hide Custom Fields from Options screen (when custom fields are not supported)

[Guido07111975]

Hi,

Although support for Custom Fields is not declared while registering a post type, the Custom Fields checkbox is still being displayed at the Options screen. Check attachment. Same applies when removing the Custom Fields metabox from editor by using remove_meta_box.
But it's not possible to activate the Custom Fields panel in the editor. Checkbox stays empty.
Custom Fields must be hidden from the Options screen.
In classic editor no issue.

And the "Post" attributes label for posts is accidentally called "Page" attributes. Check attachment.

Guido