feat: detect the drift and retrain the index if hit threshold

[BubbleCal]

Today we provide 2 ways for users to maintain the vector index:

• create_index: create a new index on the entire dataset
• optimize: incrementally index on the unindexed rows

it's recommended that the users should call optimize for shorter indexing time, but the index might be not accurate as inserting more rows.

this PR introduces:

• record the loss of each delta index
• force to retrain the index on all rows if avg_loss > original_avg_loss * THRESHOLD
• support to train KMeans from existing centroids to significantly improve the indexing perf

after this, the users don't need to call create_index to create a new index to replace existing one, optimize would detect the avg loss, and retrain the index in more efficient way

[BubbleCal]

this is never used, so remove it

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 82.93839% with 72 lines in your changes missing coverage. Please review.

Project coverage is 78.84%. Comparing base (0487ff5) to head (52b27c7).
Report is 8 commits behind head on main.

Files with missing lines	Patch %	Lines
rust/lance/src/index/vector/ivf.rs	74.69%	11 Missing and 10 partials ⚠️
rust/lance-linalg/src/kmeans.rs	74.28%	9 Missing ⚠️
rust/lance/src/index/vector/ivf/v2.rs	95.50%	8 Missing ⚠️
rust/lance-index/src/vector/hnsw/index.rs	0.00%	6 Missing ⚠️
rust/lance/src/index/vector/builder.rs	89.65%	1 Missing and 5 partials ⚠️
rust/lance/src/index/vector/pq.rs	14.28%	6 Missing ⚠️
rust/lance/src/index/vector/fixture_test.rs	20.00%	4 Missing ⚠️
rust/lance-index/src/vector/ivf.rs	0.00%	3 Missing ⚠️
rust/lance-index/src/vector/ivf/storage.rs	75.00%	3 Missing ⚠️
rust/lance/src/session/index_extension.rs	0.00%	3 Missing ⚠️
... and 2 more

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3489      +/-   ##
==========================================
+ Coverage   78.66%   78.84%   +0.18%     
==========================================
  Files         254      254              
  Lines       95025    95690     +665     
  Branches    95025    95690     +665     
==========================================
+ Hits        74751    75447     +696     
+ Misses      17250    17124     -126     
- Partials     3024     3119      +95     

Flag	Coverage Δ
unittests	78.84% <82.93%> (+0.18%)	⬆️

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