tty: document `WriteStream.cursorTo()` and others

Adds documentation for the following `WriteStream` instance methods:

- `WriteStream.clearLine()`
- `WriteStream.clearScreenDown()`
- `WriteStream.cursorTo()`
- `WriteStream.getWindowSize()`
- `WriteStream.moveCursor()`

PR-URL: https://github.com/nodejs/node/pull/22893
Fixes: https://github.com/nodejs/node/issues/9853


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Vse Mozhet Byt <vsemozhetbyt@gmail.com>