message: Adds proper Mnemonic text for DesignateCharset command.
diff: @@ -344,7 +344,9 @@ class MnemonicBuilder {
  else
  build("DECKPNM", "Keypad Numeric Mode");
  }
  - void operator()(DesignateCharset) { build("TODO"); }
  + void operator()(DesignateCharset const& v) {
  + build("CHARSET", fmt::format("Designate charset {} into {}.", to_string(v.charset), to_string(v.table)));
  + }
  void operator()(SingleShiftSelect const& v) {
  switch (v.table) {
  case CharsetTable::G0:
  