splunk: fix translation of IN, LIKE, and MATCHES [#789]

[pcoccoli]

Closes #789

[codecov]

Codecov Report

Merging #969 (4f1d19c) into develop (d01f91e) will increase coverage by 0.01%.
The diff coverage is 73.33%.

@@             Coverage Diff             @@
##           develop     #969      +/-   ##
===========================================
+ Coverage    64.68%   64.70%   +0.01%     
===========================================
  Files          517      517              
  Lines        48849    48855       +6     
===========================================
+ Hits         31600    31612      +12     
+ Misses       17249    17243       -6     

Impacted Files	Coverage Δ
.../tests/stix_translation/test_splunk_stix_to_spl.py	73.04% <71.42%> (+2.17%)	⬆️
...dules/splunk/stix_translation/query_constructor.py	71.09% <75.00%> (+0.43%)	⬆️
...hifter_modules/splunk/stix_translation/encoders.py	71.42% <0.00%> (+14.28%)	⬆️

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