Comments being later approved don't come over with Content Refresh

Imagine having post that will be imported with the Content Diff Migrator. If the post has comments that are not still approved, the `comment_count` column for the Post will be 0. [This check](https://github.com/Automattic/newspack-content-diff-migrator/blob/71ee6691c79bd5458a20d648eb5b040e204004c8/src/Logic/ContentDiffMigrator.php#L395) will prevent those comment from being imported.

However, during the double-posting period, those comments can be approved and we will end up with a post without comments.

CC: @iuravic @kariae

Start in src/Logic/ContentDiffMigrator.php around the linked comment_count check and trace how Content Refresh decides which comments to import. Confirm the behavior for comments that become approved during the double-posting period; done means the refreshed post includes those comments instead of remaining without them.

Written by the indexing model from the issue text.