http-backend: new rpc-service for git-upload-archive

http-backend: new rpc-service for git-upload-archive

Add new rpc-service "upload-archive" in http-backend to add server side
support for remote archive over HTTP/HTTPS protocols.

Also add new test cases in t5003. In the test case "archive remote http
repository", git-archive exits with a non-0 exit code even though we
create the archive correctly. It will be fixed in a later commit.

Helped-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Jiang Xin <zhiyou.jx@alibaba-inc.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>