…ducer

The 1.7.0 fix for GHSA-3r75-xc34-5f44 wired the same-hostname enqueue
strategy into SitemapRequestLoader._passes_filters, but the lower-level
parse_sitemap / Sitemap.load / Sitemap.try_common_names API still
accepted every nested-sitemap <loc> and every <urlset><url><loc>
regardless of host. A sitemap on attacker.example could push
http://127.0.0.1:... or http://169.254.169.254/... into the queue, and
_fetch_and_process_sitemap would dispatch the request through the
configured HTTP client.

Move the filter_url check from SitemapRequestLoader._passes_filters down
into _process_sitemap_item so the same policy applies to both pipelines.
ParseSitemapOptions gains an enqueue_strategy field (default
'same-hostname', matching the loader default added in PR #1864). The
strategy is threaded through _process_raw_source and
_fetch_and_process_sitemap so producer-side filtering runs whether the
sitemap content arrived as a raw blob or via the HTTP client.

SitemapRequestLoader now stamps its configured enqueue_strategy into
ParseSitemapOptions, so its existing _passes_filters call remains
defence-in-depth rather than the sole gate. Callers that legitimately
need cross-host sitemap discovery opt in with
ParseSitemapOptions(enqueue_strategy='same-domain') / 'all'.

Note: this closes the URL-injection (read-back) path. A blind GET
against the redirect target can still occur because the HTTP-client
stream() follows 3xx with follow_redirects=True; closing that fully
needs a hook on stream() to re-run filter_url after redirect. Out of
scope for the minimal producer-side fix; tracked as a follow-up.

Signed-off-by: tonghuaroot <tonghuaroot@gmail.com>