c56e94af2d
Rather than make each ipn.StateStore implementation guard against useless writes (a write of the same value that's already in the store), do writes via a new wrapper that has a fast path for the unchanged case. This then fixes profileManager's flood of useless writes to AWS SSM, etc. Updates #8785 Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>