feat: add initial scanner statistics

[westonpace]

This just captures some very basic statistics. I'd like to eventually add bytes read, decode time, and time waiting on I/O to the mix. However, those will need to wait for https://github.com/lancedb/lance/issues/2977 because those stats will go in the scheduler and we want one scan scheduler to be used in the entire plan first.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 56.77966% with 51 lines in your changes missing coverage. Please review.

Project coverage is 78.78%. Comparing base (bfacd7c) to head (5b84e93). Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
rust/lance/src/dataset/scanner/stats.rs	45.94%	40 Missing :warning:
rust/lance/src/dataset/scanner.rs	71.79%	7 Missing and 4 partials :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3075      +/-   ##
==========================================
- Coverage   78.85%   78.78%   -0.08%     
==========================================
  Files         250      251       +1     
  Lines       91474    91641     +167     
  Branches    91474    91641     +167     
==========================================
+ Hits        72134    72196      +62     
- Misses      16379    16479     +100     
- Partials     2961     2966       +5     

Flag	Coverage Δ
unittests	78.78% <56.77%> (-0.08%)	:arrow_down:

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