Decode URL for chinese file name

[FullStackEngN]

If URL contains Chinese file name, then URL will be encode.
So when the server get the URL, it need decode it firstly.

For example,

If user send this URL:
http://sp16:8081/wopi/files/工作簿1.xlsx?access_token=123

Then browser will encode it, and server get this URL:
http://sp16:8081/wopi/files/%E5%B7%A5%E4%BD%9C%E7%B0%BF1.xlsx?access_token=123

So server need decode it to get the right file name.

[FullStackEngN]

Read the doc again, and found the file id should only contain letters and numbers, so Chinese file name is not legal here.
Maybe this is not a good pull request, but if we add this, then it's easy for test purpose.