Userland: Avoid some conversions from rvalue strings to StringView

These are all actually fine, there is no UAF here. But once e.g.
`ByteString::view() &&` is deleted, these instances won't compile.

Userland/Libraries/LibWebSocket/WebSocket.cpp

@@ -219,7 +219,7 @@ void WebSocket::send_client_handshake()
     builder.append("\r\n"sv);
 
     m_state = WebSocket::InternalState::WaitingForServerHandshake;
-    auto success = m_impl->send(builder.to_byte_string().bytes());
+    auto success = m_impl->send(builder.string_view().bytes());
     VERIFY(success);
 }