Let hash functions take a digest::Digest trait

... and add adapters for current Sha512 implementations that does not inplement the Digest trait

embassy-boot/boot/src/digest_adapters/mod.rs

@@ -0,0 +1,5 @@
+#[cfg(feature = "ed25519-dalek")]
+pub(crate) mod ed25519_dalek;
+
+#[cfg(feature = "ed25519-salty")]
+pub(crate) mod salty;