[Distributed][Macro] Imrpve diagnostics, skip copying assoc types etc.

Author: ktoso

lib/Macros/Sources/SwiftMacros/DistributedProtocolMacro.swift

@@ -49,6 +49,14 @@ extension DistributedProtocolMacro {
 
     let requirementStubs =
       proto.memberBlock.members // requirements
+        .filter { member in
+          switch member.decl.kind {
+          case .functionDecl: return true
+          case .variableDecl: return true
+          default:
+            return false
+          }
+        }
         .map { member in
           stubMethodDecl(access: accessModifiers, member.trimmed)
         }