Automatically set /dev/tty as STDIN on execute action

https://github.com/junegunn/fzf/issues/1360#issuecomment-788178140

  # Redirect /dev/tty to suppress "Vim: Warning: Input is not from a terminal"
  ls | fzf --bind "enter:execute(vim {} < /dev/tty)"

  # With this change, we can omit "< /dev/tty" part
  ls | fzf --bind "enter:execute(vim {})"

src/tui/ttyname_windows.go

@@ -2,6 +2,13 @@
 
 package tui
 
+import "os"
+
 func ttyname() string {
 	return ""
 }
+
+// TtyIn on Windows returns os.Stdin
+func TtyIn() *os.File {
+	return os.Stdin
+}