When Leonard updated CLI11 in #12658, he imported a version that no
longer requires RTTI. Since CLI11 was the only reason we had enabled
RTTI in any of our projects, we're finally able to turn it off.
| | TerminalApp.dll | MSIX Package |
| ------ | ---------------:| ------------:|
| Before | 3180KiB | 6545KiB |
| After | 1970KiB | 6426KiB |
| Delta | **-1210KiB** | **-119KiB** |