feat: add APIs for time-travel read

[xushiyan]

Add new table APIs read_snapshot() and read_snapshot_as_of() for snapshot and time travel reads.

[codecov]

Codecov Report

Attention: Patch coverage is 90.00000% with 7 lines in your changes missing coverage. Please review.

Project coverage is 90.63%. Comparing base (d5f2231) to head (83485d0).

Files	Patch %	Lines
crates/core/src/table/mod.rs	81.81%	4 Missing ⚠️
crates/core/src/table/timeline.rs	88.88%	2 Missing ⚠️
crates/datafusion/src/lib.rs	66.66%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #33      +/-   ##
==========================================
- Coverage   90.92%   90.63%   -0.30%     
==========================================
  Files          10       10              
  Lines         463      491      +28     
==========================================
+ Hits          421      445      +24     
- Misses         42       46       +4     

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