Importing page items doesn't support multisite

[hissy]

Affected Version of Concrete CMS

9.x

Description

\Concrete\Core\Backup\ContentImporter\ValueInspector\Item\PageItem will get pages only from the default site.

How to reproduce

1. Enable multisite
2. Export content with migration tool from the default site
3. Import content with migration tool to the second site
4. All links will be connected to the default site

Possible Solution

Better to get the current site from the site service.

Additional Context

Concrete\Package\MigrationTool\Backup\ContentImporter\ValueInspector\Item\BatchPageItem class shouldn't call the getContentObject() method in the core PageItem class. When we import contents with the Migration Tool, we should try to get the already imported page from the site that is connected with the current batch, instead of the site that is detected from the site service.