Inconsistent NEOFS_NETWORK_DOMAIN parameter

[roman-khimov]

Current Behavior

NEOFS_NETWORK_DOMAIN is about some domain, previously we've used it as a generic top-level domain and workflow automatically added stX to it. Now it's a node address effectively which is OK (allows to use private nodes, for example), but it's somewhat misleading in its name and also missing any ability to specify port. It's also unobvious if it supports scheme specification (grpcs://, anyone?).

Expected Behavior

Have some NEOFS_NODE or NEOFS_ENDPOINT parameter that accepts a simple string that is used for RPC endpoint.

Possible Solution

Will require 0.2.0 since it's a breaking change (but we can think of some deprecation/compat in 0.1.3).