Limit Dictionary to Single Level

[oerling]

• Modifies wrapInDictionary to flatten indices of a wrapped dictionary iwth the wrapping indices.
• Makes lazy loading of a dictionary encoded column to combine the indices with a dictionary wrapper if loading with lazy wrapped in a dictionary.
• Adds functions to transpose dictionaries with and without nulls.
• Changes NestedLoopJoin and MergeJoin so that they wrap their input only after the wrapping indices are known. Previously these would wrap first and only then fill in the indices.
• Checks that we do not come across multiple nested dictionaries.

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This pull request has been automatically marked as stale because it has not had recent activity. If you'd still like this PR merged, please comment on the PR, make sure you've addressed reviewer comments, and rebase on the latest main. Thank you for your contributions!