Add custom font functionality | 添加自定义字体功能

[rong6]

CN：
在中文模式下，有很多汉字显示错误，这可能是字库缺失导致的，同时，我有自定义字体的需求，可否在“设置”中添加自定义字体的功能，这样我们就可以自行替换字体以防止字体出错及更加丰富的功能。

EN：
In Chinese, there are many Chinese character display errors, which may be caused by the lack of fonts. At the same time, I have the need to customize fonts. Can I add the function of custom fonts in "Settings" so that we can replace the fonts ourselves? Prevent font errors and provide richer functions.