LibCrypto: Make `Digest`s able to return `bytes`

Userland/Libraries/LibCrypto/Hash/HashFunction.h

@@ -21,6 +21,8 @@ struct Digest {
 
     [[nodiscard]] ALWAYS_INLINE const u8* immutable_data() const { return data; }
     [[nodiscard]] ALWAYS_INLINE size_t data_length() const { return Size; }
+
+    [[nodiscard]] ALWAYS_INLINE ReadonlyBytes bytes() const { return { immutable_data(), data_length() }; }
 };
 
 template<size_t BlockS, size_t DigestS, typename DigestT = Digest<DigestS>>

Userland/Libraries/LibCrypto/Hash/HashManager.h

@@ -73,6 +73,13 @@ struct MultiHashDigestVariant {
             [&](const auto& value) { return value.data_length(); });
     }
 
+    [[nodiscard]] ReadonlyBytes bytes() const
+    {
+        return m_digest.visit(
+            [&](const Empty&) -> ReadonlyBytes { VERIFY_NOT_REACHED(); },
+            [&](const auto& value) { return value.bytes(); });
+    }
+
     using DigestVariant = Variant<Empty, MD5::DigestType, SHA1::DigestType, SHA256::DigestType, SHA384::DigestType, SHA512::DigestType>;
     DigestVariant m_digest {};
 };

Userland/Utilities/checksum.cpp

@@ -64,8 +64,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
         while (!file->eof() && !file->has_error())
             hash.update(file->read(PAGE_SIZE));
-        auto digest = hash.digest();
-        outln("{:hex-dump}  {}", ReadonlyBytes(digest.immutable_data(), digest.data_length()), path);
+        outln("{:hex-dump}  {}", hash.digest().bytes(), path);
     }
     return has_error ? 1 : 0;
 }