Add sv2 noise protocol

Co-Authored-By: Christopher Coverdale <chris.coverdale24@gmail.com>

Author: Sjors

src/pubkey.h

@@ -319,7 +319,7 @@ struct EllSwiftPubKey
     /** Construct a new ellswift public key from a given serialization. */
     EllSwiftPubKey(Span<const std::byte> ellswift) noexcept;
 
-    /** Decode to normal compressed CPubKey (for debugging purposes). */
+    /** Decode to normal compressed CPubKey. */
     CPubKey Decode() const;
 
     // Read-only access for serialization.

src/sv2/CMakeLists.txt

@@ -3,6 +3,7 @@
 # file COPYING or https://opensource.org/license/mit/.
 
 add_library(bitcoin_sv2 STATIC EXCLUDE_FROM_ALL
+  noise.cpp
 )
 
 target_link_libraries(bitcoin_sv2