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>

performance-metrics/src/micro_bench_block.rs

@@ -13,7 +13,7 @@ use std::time::Instant;
 
 use block::async_io::AsyncIoOperation;
 use block::disk_file::AsyncDiskFile;
-use block::raw_disk::{RawBackend, RawDisk};
+use block::formats::raw::{RawBackend, RawDisk};
 
 use crate::PerformanceTestControl;
 use crate::util::{