x-terminal-emulator does not exist in non-debian distros

[DevAlien]

We have to better handle how we handle the run-in-emulator.

This is how vscode does it: https://github.com/microsoft/vscode/blob/50e3593171298d20cf7f8b8600f7a3ab90d16b3a/src/vs/workbench/contrib/externalTerminal/node/externalTerminalService.ts#L303-L328