Remove winpty support (#289025)

* Bump node-pty to 1.2.0-beta.7

* Deprecate TerminalSettingId.WindowsEnableConpty setting

* Remove windowsEnableConpty instead of deprecating

* Remove WINPTY from ps.ts

* Remove winpty from appropriate comments

* Remove winpty from IProcessReadyWindowsPty

* Remove from classifier.json. TODO on resize for node-pty

* Try adding option to test

* Add reference to issue