When user click exit button terminal process will not be killed if terminal has child processes.

[AndrienkoAleksandr]

Reproduction Steps:

1. Create new terminal.
2. Open Midnight Commander (mc) in the teminal.
3. Click close button.
   Expected behavior:
   Terminal process and child processes should be killed.

Observed behavior:
Terminal process is still alive, but mc process was killed.

PS: When we click close button our UI send exit command. Exit command can kill terminal if terminal hasn't child process. If terminal has child processes then exit command can be redirected to the child process, for example mc, and terminal is alive. I think we should implement special command to kill terminal and child processes of the terminal.

Che version: 5.0.0-M8-SNAPSHOT

Additional information:

• Problem started happening recently, didn't happen in an older version of Che: [No]
• Problem can be reliably reproduced, doesn't happen randomly: [Yes]