block: Remove raw_disk compat alias

Update external consumers and internal test modules to use
formats::raw instead of the raw_disk alias, then remove the
re-export from lib.rs.

Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>

fuzz/fuzz_targets/block.rs

@@ -16,7 +16,7 @@ use std::sync::Arc;
 use std::{ffi, io};
 
 use block::fcntl::LockGranularityChoice;
-use block::raw_disk::{RawBackend, RawDisk};
+use block::formats::raw::{RawBackend, RawDisk};
 use libfuzzer_sys::{fuzz_target, Corpus};
 use seccompiler::SeccompAction;
 use virtio_devices::{Block, VirtioDevice, VirtioInterrupt, VirtioInterruptType};