feat: expose datafusion query execution apis

[ChunxuTang]

This PR

• exposes three public datafusion query execution APIs
  • execute_datafusion: execute using the DataFusion planner with in-memory datasets. This is the API similar to the current execute
  • execute_datafusion_with_context: execute query with a DataFusion SessionContext, automatically building the catalog
  • execute_datafusion_with_catalog_and_context: execute query with a user-built catalog and session context. This is the most flexible datafusion-based API.
• fixes the unqualified column names issue
• adds more integration tests

[codecov-commenter]

Codecov Report

❌ Patch coverage is 94.11765% with 22 lines in your changes missing coverage. Please review.
⚠️ Please upload report for BASE (main@e89fe95). Learn more about missing BASE report.

Files with missing lines	Patch %	Lines
rust/lance-graph/src/datafusion_planner.rs	90.83%	11 Missing ⚠️
rust/lance-graph/src/query.rs	95.66%	11 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #28   +/-   ##
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  Coverage        ?   79.76%           
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  Files           ?       16           
  Lines           ?     7073           
  Branches        ?        0           
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  Hits            ?     5642           
  Misses          ?     1431           
  Partials        ?        0           

Flag	Coverage Δ
rust-unittests	79.76% <94.11%> (?)

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