Additional API calls related to entity upgrades

[unhott]

https://lua-api.factorio.com/latest/eve ... or_upgrade uses the terminology 'target' , so I think it would be nice to have the ability to say something along the lines of
luaEntity.get_upgrade_target --> luaPrototype
luaEntity.upgrade() similar to .revive() which leverages multiple return values.

[Bilka]

These were added as LuaEntity::get_upgrade_target() and LuaEntity::apply_upgrade().