extending set_value_labels() to vectors

[larmarange]

fix #126

still exploratory

similarly, set_varaiable_labels(), set_na_values() and set_na_range() should be updated as well

[codecov[bot]]

Codecov Report

Merging #127 (72f7475) into main (2ac2875) will decrease coverage by 0.76%. The diff coverage is 79.54%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #127      +/-   ##
==========================================
- Coverage   95.55%   94.79%   -0.77%     
==========================================
  Files          17       17              
  Lines         878      922      +44     
==========================================
+ Hits          839      874      +35     
- Misses         39       48       +9     

Impacted Files	Coverage Δ
R/na_values.R	92.56% <71.42%> (-2.77%)	:arrow_down:
R/val_labels.R	94.82% <82.60%> (-1.87%)	:arrow_down:
R/var_label.R	98.14% <85.71%> (-1.86%)	:arrow_down: