feature - handle signals

[biralavor]

Our subject says:

• Handle ctrl-C, ctrl-D and ctrl-\ which should behave like in bash.
• In interactive mode: ◦ ctrl-C displays a new prompt on a new line. ◦ ctrl-D exits the shell. ◦ ctrl-\ does nothing.

Reference: https://www.codequoi.com/en/sending-and-intercepting-a-signal-in-c/