vmm: Introduce kernel hashes measured boot

This introduces the kernel hashes measured boot table into
cloud hypervisor if a cmdline and kernel is passed into an
SEV-SNP CVM, incorporating a kernel/cmdline/optional initrd
into a memory page that is measured into the launch digest
of a SEV-SNP CVM. If both --kernel and --cmdline are not
provided, we do not insert this data page

Signed-off-by: Kevin Hui <kevinhui@meta.com>

vmm/Cargo.toml

@@ -81,6 +81,7 @@ seccompiler = { workspace = true }
 serde = { workspace = true, features = ["derive", "rc"] }
 serde_json = { workspace = true }
 serial_buffer = { path = "../serial_buffer" }
+sha2 = { workspace = true }
 signal-hook = { workspace = true }
 thiserror = { workspace = true }
 tracer = { path = "../tracer" }