Add HBM3E mapping to Redfish memory type translation.

When the D-Bus `MemoryType` property on `xyz.openbmc_project.Inventory.Item.Dimm` is set to `xyz.openbmc_project.Inventory.Item.Dimm.DeviceType.HBM3E`, `translateMemoryTypeToRedfish()` previously returned an empty string because its whitelist stopped at `HBM3`, causing `MemoryDeviceType` to be omitted from Redfish `Memory` resources.

Add the `HBM3E` mapping to `translateMemoryTypeToRedfish()` in `memory.h`, along with unit test coverage in `memory_test.cc`.

Google-Bug-Id:555368649,564635742
PiperOrigin-RevId: 988436919
Change-Id: Ibbd6b907f5d5efb90dd253616854f6502a025a56