Fix a few Coverity warnings from the session manager work

- Be explicit about setting the copied flag in session::Key. Coverity seems
  confused about when that flag is set if it gets set by default
  initialization. This should fix 1452757 and 1452759.
- Explicitly copy the fields in ConnKey instead of using memcpy. Fixes
  1452758.

src/session/Key.cc

@@ -7,8 +7,11 @@ namespace zeek::session::detail {
 Key::Key(const void* session, size_t size, bool copy) : size(size)
 	{
 	data = reinterpret_cast<const uint8_t*>(session);
+
 	if ( copy )
 		CopyData();
+
+	copied = copy;
 	}
 
 Key::Key(Key&& rhs)