Add --tty-default=/dev/tty and --no-tty-default option (#4352)

Fix #4242.

Use --no-tty-default, if you want fzf to perform a TTY look-up instead of defaulting to /dev/tty.

src/proxy.go

@@ -145,7 +145,7 @@ func runProxy(commandPrefix string, cmdBuilder func(temp string, needBash bool)
 					env = elems[1:]
 				}
 				executor := util.NewExecutor(opts.WithShell)
-				ttyin, err := tui.TtyIn()
+				ttyin, err := tui.TtyIn(opts.TtyDefault)
 				if err != nil {
 					return ExitError, err
 				}