Support environment which uploads binary file (Currently Golang)

[yqf3139]

FIssion just landed the golang environment support.The golang .so file is using the function's code field to upload/download binary file, which is used as the text file by other environment now.

It is difficult for fission-ui to distinguish whether the file is binary or not to enable function editing. So the bug will be fixed until we land a feature in fission to tell whether the file is binary or not, or further more the environment v2 model.

Currently we can use batch upload to create golang env functions. However, it is buggy now because we are trying to read an binary file as string and encode it in base64.