ionic serve clear terminal on reload

I think it would be nice to have the option to pass a argument to ionic serve to clear the terminal output. For example "ionic serve --clear" or similar.

This would make the terminal cleaner and easier to identify errors and warnings in the terminal when developing.

I know that for example Vue does it like this.

首先定位 ionic serve 指令及其引數的解析方式。檢查 reload 輸出是如何產生的，然後定義 clear 選項的行為，並驗證 reload 會清除終端機，同時現有的 serve 輸出和錯誤仍可正常使用。

由索引模型根據 Issue 內容生成。