Description of the new feature/enhancement

This feature request is related to this feature request:

https://github.com/microsoft/terminal/issues/4379

Essentially, the ability to customize what key/key sequences reopens or closes a profile session. Currently Ctrl+D will close the terminal after exit and "Enter" will restart it. I would like to customize it so that "r" will restart the session and "" or "" will close the session for good. This is what MobaXterm uses and it would be nice to have it consistent as I use both regularly.

Proposed technical implementation details (optional)

Something like this in the json file:

"closeOnExit": "never", { "closeKey": "", "reopenKey": "r" }