Fix bug with NumWords; add test suite

[sbadithe]

• Fix NumWords returns wrong answer when text with multiple spaces is passed in  #2457
• Add missing test suite for NumWords

[codecov]

Codecov Report

Merging #2459 (02fcd62) into main (931cc70) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main    #2459   +/-   ##
=======================================
  Coverage   99.41%   99.41%           
=======================================
  Files         343      344    +1     
  Lines       21056    21106   +50     
=======================================
+ Hits        20932    20982   +50     
  Misses        124      124           

Impacted Files	Coverage Δ
...s/standard/transform/natural_language/num_words.py	100.00% <100.00%> (ø)
...atural_language_primitives_tests/test_num_words.py	100.00% <100.00%> (ø)
...s/tests/primitive_tests/test_transform_features.py	99.87% <100.00%> (ø)

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