termios: new termios module (#17792)

* termio: new termio module

move the tcgetattr and tcsetattr functions in a new termio module.
The code needed refactoring as different OS have different fields
size, position and number for the C.termios structure, which
could not be correctly expressed consitently otherwise.

It has the positive side effect to reduce the number of unsafe calls.
New testing code was also added for the readline module as it is
relying of the feature.

* apply 2023 copyright to the new files too

vlib/readline/readline.v

@@ -7,6 +7,8 @@
 //
 module readline
 
+import term.termios
+
 // Winsize stores the screen information on Linux.
 struct Winsize {
 	ws_row    u16
@@ -20,9 +22,9 @@ struct Winsize {
 pub struct Readline {
 mut:
 	is_raw            bool
-	orig_termios      Termios // Linux
-	current           []rune  // Line being edited
-	cursor            int     // Cursor position
+	orig_termios      termios.Termios // Linux
+	current           []rune // Line being edited
+	cursor            int    // Cursor position
 	overwrite         bool
 	cursor_row_offset int
 	prompt            string