Move QMCDriverNew::putWalkers outside of QMCDriver

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The driver shouldn't know anything about the XML input. `void QMCDriverNew::putWalkers(std::vector& wset)` violates that pattern.

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Move the XML parsing outside fo QMCDriverNew

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Start by locating QMCDriverNew::putWalkers and trace how XML input reaches it. Separate the XML parsing from QMCDriverNew while preserving walker setup behavior; done means the driver no longer depends on XML nodes and existing behavior remains intact.

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