ask-password: rework how we pass request meta info when asking passwords

Rather than adding more and more parameters to ask_password_auto(), let's
pass a structure of the fields that often are constant anyway.

This way, callers can fill in what they need, and we take the filled
structure which we can pass around internally as one.

This is in particular preparation for adding one more field in one of
the next commits.

src/firstboot/firstboot.c

@@ -797,7 +797,11 @@ static int prompt_root_password(int rfd) {
                 _cleanup_strv_free_erase_ char **a = NULL, **b = NULL;
                 _cleanup_free_ char *error = NULL;
 
-                r = ask_password_tty(-1, msg1, NULL, 0, 0, NULL, &a);
+                AskPasswordRequest req = {
+                        .message = msg1,
+                };
+
+                r = ask_password_tty(-EBADF, &req, /* until= */ 0, /* flags= */ 0, /* flag_file= */ NULL, &a);
                 if (r < 0)
                         return log_error_errno(r, "Failed to query root password: %m");
                 if (strv_length(a) != 1)
@@ -817,7 +821,9 @@ static int prompt_root_password(int rfd) {
                 else if (r == 0)
                         log_warning("Password is weak, accepting anyway: %s", error);
 
-                r = ask_password_tty(-1, msg2, NULL, 0, 0, NULL, &b);
+                req.message = msg2;
+
+                r = ask_password_tty(-EBADF, &req, /* until= */ 0, /* flags= */ 0, /* flag_file= */ NULL, &b);
                 if (r < 0)
                         return log_error_errno(r, "Failed to query root password: %m");
                 if (strv_length(b) != 1)