SerialServer needs a shared header with the interface #44
Description
Follow-Up from havrious PR comments:
- https://github.com/seL4/camkes-vm/pull/42/files#r1005104147
- virtio: console multiplex and vsock support camkes-vm#36 (comment)
The SerialServer need a shared header that defines the share page content. Currently It in components/SerialServer/src/serial.c only and clients define this over and over again, so it's hard to keep this in sync everywhere.