Feature: Requesting pty for a subsystem

[InfJoker]

If implementing ssh server, one may want to configure subsystem on a server, which can be requested by client. This is crucial, if one wants to implement his own subsystem.

In ssh connection protocol, subsystem can be requested with PTY, so server may create a subsystem as a CLI app, which user can access by requesting subsystem with PTY and start his interactive session.

I want a feature, which enables requesting subsystems with PTY.

So, client first requests pty-req, then subsystem.

OpenSSH provides such a feature, but it is not on windows.

See https://github.com/ClickHouse/ClickHouse/pull/48902, for the particular need of such feature