[WIP] JSON tree algorithms refactor II: Constructing device JSON column

[shrshi]

Description

Part of #15903.
NOTE: This PR depends on the previous PR #15979 which introduces the CSR storage for the column tree.

• Identifies string columns that have nested columns as siblings, and discards them
• Matching column tree validation
• Merge device_json_column with column_tree_csr struct (non-list type)
• Merge device_json_column with column_tree_csr struct (list type)
• Tests!

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.

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