api: make .open() stream data for Azure

This employs generating temporary signed public url and then streaming
from it. The bulk of the code might be reused for other remotes.

Url streaming does resume on connection error using "Range" header and
regenerates public url too.

If remote class doesn't provide .open() then this falls back to pulling
a file and opening it locally.

setup.py

@@ -107,6 +107,7 @@ tests_requirements = [
     "jaraco.windows==3.9.2",
     "mock-ssh-server>=0.5.0",
     "moto>=1.3.14.dev55",
+    "rangehttpserver==1.2.0",
 ]
 
 if (sys.version_info) >= (3, 6):