[Feature]: Support ProxyCommand SSH Config

### Feature description

Some ssh configs might look like:

```
Host <host>
  ProxyCommand=<command>
  ServerAliveInterval 15
  ServerAliveCountMax 44
  User <user>
```

Doesn't look like waveterm supports the ProxyCommand. It would be nice if it did. I might try and pick this up myself and see how it goes.

### Implementation Suggestion

_No response_

### Anything else?

_No response_