chore: basic segment info at snapshot level

[dantengsky]

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Summary

Introduces basic segment information like the number of blocks/ rows at the snapshot level. aims to improve scan task partitioning, and also offers potential benefits for the scheduling of compaction tasks.

Tests

• [ ] Unit Test
• [x] Logic Test
• [ ] Benchmark Test
• [ ] No Test - Explain why

Type of change

• [ ] Bug Fix (non-breaking change which fixes an issue)
• [x] New Feature (non-breaking change which adds functionality)
• [ ] Breaking Change (fix or feature that could cause existing functionality not to work as expected)
• [ ] Documentation Update
• [ ] Refactoring
• [ ] Performance Improvement
• [ ] Other (please describe):

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This change is