COPY: Apply scheme https as default for endpoint url

[Xuanwo]

Summary

Allow query like:

COPY INTO default.test FROM 's3://helloworld/databend-autoloader-e2e-test' CONNECTION = (ENDPOINT_URL = 's3.amazonaws.com');

If users input a URL without scheme, use https as default.

[Xuanwo]

Cc @ClSlaid for help.

[ClSlaid]

Now that FTP is merged, I'll finish this.