Allow to edit page title when using Layout Builder variant

Patch applies to latest dev and mostly works. The "title" is being set but the metatitle is still showing as the title used to create the page.. which doesn't seem to be editable.

Could someone please turn this into a MR instead of patches?

The patch works for me but I ran into a bit of an edge case here - the current LayoutBuilderDisplayVariant::build() implementation as in the patch / pull request builds blocks in the order they were added, not their weight as Drupal\layout_builder\Section::toRenderArray() would.

Leveraging Drupal\layout_builder\Section::getComponentsByRegion() to sort the blocks by weight as in Drupal\layout_builder\Section::toRenderArray(), fixes the issue:

/**
 * {@inheritdoc}
 */
public function build() {
  $build = [];
  $contexts = $this->getContexts();
  $in_preview = FALSE;

  /** @var \Drupal\layout_builder\Section $section */
  foreach ($this->getSections() as $delta => $section) {
    $layout_definition = $section->getLayout()->getPluginDefinition();
    foreach ($layout_definition->getRegionNames() as $region) {
      foreach ($section->getComponentsByRegion($region) as $component) {
        if ($block = $component->toRenderArray($contexts, $in_preview)) {
          if ($this->configuration['title_type'] === 'block' && $this->configuration['title_from_block'] === $uuid) {
            $build['#title'] = $this->getBlockTitle($block);
            $block['#configuration']['label_display'] = 0;
          }

          $regions[$component->getRegion()][$component->getUuid()] = $block;
        }
      }
    }
    $build[$delta] = $section->getLayout()->build($regions);
  }

  if ($this->configuration['title_type'] === 'manual') {
    $build['#title'] = $this->renderManualPageTitle($this->configuration['manual_title']);
  }

  return $build;
}

I'm attaching a patch with the change I described above, for reference. It adjusts the build order by using Drupal\layout_builder\Section::getComponentsByRegion(), aligning with Drupal\layout_builder\Section::toRenderArray() behavior and fixing the edge case with block weights.