Move idn_test_case_generator.py to components/url_formatter.

This script generates test cases for idn_spoof_checker_unittest.cc,
so it should move to the same directory as that test, and be owned
by the owners of that test.

Update the only references to this file to reflect the new location.

This is the last step before removing the tools/security directory
(which was largely ignored).

Bug: 40271693
Change-Id: I6cee4b52532f703849c4fbdbfc5033167200d90d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6227640
Commit-Queue: Tom Sepez <tsepez@chromium.org>
Reviewed-by: Emily Stark <estark@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1415296}