message: Improve WriteCharsLegacy performance by increasing local buffer size
  Improve WriteCharsLegacy performance by increasing LocalBuffer size, allowing
  longer runs of characters to be submitted to the remaining parts of conhost.
  References -- vtebench tracking issue
  ## Validation Steps Performed
  * Ran `cat big.txt`, vtebench and termbench and
  noted ~5% performance improvements
diff: @@ -28,8 +28,6 @@ using Microsoft::Console::VirtualTerminal::StateMachine;
  // Used by WriteCharsLegacy.
  #define IS_GLYPH_CHAR(wch) (((wch) >= L' ') && ((wch) != 0x007F))
  -constexpr unsigned int LOCAL_BUFFER_SIZE = 100;
  -
  // Routine Description:
  // - This routine updates the cursor position. Its input is the non-special
  // cased new location of the cursor. For example, if the cursor were being
  @@ -339,7 +337,6 @@ constexpr unsigned int LOCAL_BUFFER_SIZE = 100;
  COORD CursorPosition = cursor.GetPosition();
  NTSTATUS Status = STATUS_SUCCESS;
  SHORT XPosition;
  - WCHAR LocalBuffer[LOCAL_BUFFER_SIZE];
  size_t TempNumSpaces = 0;
  const bool fUnprocessed = WI_IsFlagClear(screenInfo.OutputMode, ENABLE_PROCESSED_OUTPUT);
  const bool fWrapAtEOL = WI_IsFlagSet(screenInfo.OutputMode, ENABLE_WRAP_AT_EOL_OUTPUT);
  @@ -360,6 +357,9 @@ constexpr unsigned int LOCAL_BUFFER_SIZE = 100;
  coordScreenBufferSize.X = textBuffer.GetLineWidth(CursorPosition.Y);
  }
  + static constexpr unsigned int LOCAL_BUFFER_SIZE = 1024;
  + WCHAR LocalBuffer[LOCAL_BUFFER_SIZE];
  +
  while (*pcb < BufferSize)
  {
  // correct for delayed EOL
  