rpclib: rename .cc files for compatibilty with latest arduino-cli

Author: facchinm

libraries/rpclib/src/rpc/detail/client_error.cc

@@ -21,4 +21,6 @@ timeout::timeout(std::string const &what_arg) : std::runtime_error(what_arg) {
 
 const char *timeout::what() const noexcept { return formatted.data(); }
 
+const char* system_error::what() const noexcept { return std::system_error::what(); }
+
 } /* rpc */