Speeded up min_max_boolean for the case where all values are null

[HaoYang670]

Signed-off-by: remzi 13716567376yh@gmail.com

Changes in the PR:
For a Boolean array without null value. We can simply get the max value by testing array.values.null_count < array.length and get the min value by testing array.values.null_count == 0.
Theoretically, the time complexity is O(1) as null_count is pre computed.

[codecov]

Codecov Report

Merging #1005 (6fc959f) into main (a810b03) will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #1005      +/-   ##
==========================================
+ Coverage   71.44%   71.45%   +0.01%     
==========================================
  Files         356      356              
  Lines       19752    19758       +6     
==========================================
+ Hits        14112    14119       +7     
+ Misses       5640     5639       -1     

Impacted Files	Coverage Δ
src/compute/aggregate/min_max.rs	75.36% <100.00%> (+1.11%)	⬆️
src/bitmap/utils/slice_iterator.rs	87.93% <0.00%> (+1.72%)	⬆️

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[jorgecarleitao]

Thanks a lot, @HaoYang670 , indeed it is a quite faster case :)