Upgrade/downgrade a remote cluster

[Totktonada]

Context

The new database upgrading/downgrading tool is proposed in #924 -- see more background context here.

Since I've filed this issue, I've consulted with @psergee and @oleg-jukovec and found that a support of remote instances requires some separate work. This is why the separate issue is created.

Proposal

Add some way to work with remote instances in upgrading/downgrading commands.

If it requires to write some file with URLs, logins, passwords -- OK. It does the job.

I think that the optimal solution would be extracting these URLs/logins/passwords from a cluster configuration written in the tarantool 3.x format.

It works even for upgrading from 1.10 to 2.11: we use the cluster configuration for tt, while tarantool instances are configured on its own. (Moreover, in a future we may have a tooling that converts cartridge configuration to 3.x configuration and it would simplify the things.)

Also tracked in TNTP-363
Part of TNTP-41