Override a non-indexed bundle on a per-entity basis

Any updates here? Allowing individual entities to be indexed even if the bundle is excluded is quite a common need. Seems like the latest patch breaks module functionality.

Here's a version of the patch against 4.x. It does the following:

* Removes the form alter that disables per-entity overrides.
* Adds a method getAllowedEntities() to the EntityManager service
* Call that method from the EntityUrlGenerator in cases where the bundle is not auto-indexed.

Based on my reading of the code, access checking is handled by EntityUrlGeneratorBase, so that is omitted.

This likely needs a test, though is seems to work in my use-case.

If you would prefer an MR, I can make one.

I added an MR -- https://git.drupalcode.org/project/simple_sitemap/-/merge_requests/119 -- and updated tests.

Something is a bit off in the test. I can't seem to get the sitemap to re-render. See this part of the test code:

    // Test sitemap result -- Not working as expected.
    # $this->generator->rebuildQueue();
    # $this->generator->generate(QueueWorker::GENERATE_TYPE_BACKEND);
    # $this->drupalGet($this->defaultSitemapUrl);
    # $this->assertSession()->responseContains('node/' . $new_node1->id());
    # $this->assertSession()->responseNotContains('node/' . $new_node2->id());

This returns a 404 instead of the sitemap. I assume that I missed a step somewhere.