Inspector Controls: add custom slot group after core slot

[t-hamano]

See: #37845

This pull request will provide a new group to the InspectorControls slot, allowing controls to be added after the typography / dimensions /border.

Currently, it is possible to inject any InspectorControls using the editor.BlockEdit filter.
However, the injected position is fixed to before typegraphy slot.

So if you inject an InspectorControl in custom block with multiple supports, the control will be inserted between the Color panel and the Typography panel.

I think that it is unnatural for a custom control to be interrupted between the panels provided by the core.

I think there needs to be a receptacle at the end of all the core controls, just before the advanced controls, where any InspectorControls can be injected.

The name of the group I added is "bottom", but there may be a better name.

Please let me know what you think about this pull request.