Support multiple slang-tidy port suffixes for EnforcePortSuffix check

[VJSchneid]

Hi folks,
this PR makes the following modifications in slang-tidy:

• Adds support to provide an array of configuration values in the slang-tidy config file ([_i, _ni]).
• Multiple (or none) port suffixes can be specified now. This enables e.g. negated ports to be specified as _ni when both _i and _ni are configured as port suffixes.
• Parsing of configValues was slightly rewritten to allow flexible parsing depending on targeted type.

[codecov]

Codecov Report

Merging #787 (c4f847b) into master (02e2354) will increase coverage by 0.00%.
The diff coverage is n/a.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #787   +/-   ##
=======================================
  Coverage   93.56%   93.57%           
=======================================
  Files         189      189           
  Lines       45650    45685   +35     
=======================================
+ Hits        42714    42748   +34     
- Misses       2936     2937    +1     

see 16 files with indirect coverage changes

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[MikePopoloski]

Thanks for the PR. I skimmed this and it looks ok to me so I'm going to merge. @Sustrak should reply as well if he thinks there are things worth changing here.