Quantile DMatrix for CPU.

[trivialfis]

This is part of #7690 to reduce memory usage of hist tree method.

• Implement Quantile DMatrix for CPU. ( Quantile DMatrix for CPU. #8130)
• Implement reference DMatrix. ( Quantile DMatrix for CPU. #8130)
• Interoperability between CPU and GPU. (Support CPU input for device QuantileDMatrix. #8136 Copy data from Ellpack to GHist. #8215)
• Make it default in sklearn interface. (Make QuantileDMatrix default to sklearn esitmators. #8220)