This pull request includes some implementations of the statistics(#6370), it Implements sql-task to collect statistics based on internal-query(#9983).
After the ANALYZE statement is parsed, statistical tasks will be generated. The statistical tasks includes mata-task(get statistics from metadata) and sql-task(get statistics by sql query). For sql-task, it will get statistics such as the row_count, the number of null values, and the maximum value by SQL query.
For statistical tasks, also include sampling sql-task, which will be implemented in the next pr.
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