Cromwell / Xromwell rebranding

Since Cromwell and Xromwell is basically the same thing, just loaded in different ways, in the XboxDev Discord we decided to rebrand Cromwell name, specifically:
- `Cromwell BIOS` to `Cromwell (ROM)`
- `Xromwell` to `Cromwell (XBE)`

The same naming scheme is used in XBlast OS.

See also discussion in #28.