For the checkpoint size project we need to update verify to do two things:

1. Verify the size of the tree as it walks it. Summing each checksum->size and then comparing against the relevant ckpt->size.
2. If given a metadata: string to verify we sum the sizes of all the trees in the database and confirm that the database size matches the summed sizes (WT-16729)

This ticket aims to do the first part

Scope:

• Implement above
• Test