Allow PCI Config space parsing to handle types

 - Update the PCI config space parsing to be able to handle multiple
   types.
 - Use a trait to abstract out reading from the config space in order to
   allow testing/fuzzing of the parser.

vesad: Fix Unicode character input

Characters beyond 0x80 now properly encoded as UTF-8.

Allow using a device ID range in toml config

ahci: refactor duplicated ATA command code into a method

ahci: Basic ATAPI support (Needed for CD drives)

It can currently retrieve the capacity; no reads or writes yet.

pcid: fix error E0133

Use capability mode (null namespace) for drivers