Allow for custom nested menu actions

[mycumycu]

This should allow mod creators to add own interact submenu positions to pre-defined 'Custom Actions' group:

[mycumycu]

Added 'Custom Orders' group and support for Allectus mods:

• https://www.nexusmods.com/x4foundations/mods/645
• https://www.nexusmods.com/x4foundations/mods/683