refactor: Consolidate config parsing for all plugin base classes

[edgarrmondragon]

Moves the processing of --config option values to detect ENV to an static method config_from_cli_args in the PluginBase class.

[codecov]

Codecov Report

Merging #1610 (4c4d912) into main (182d363) will increase coverage by 0.16%.
The diff coverage is 56.25%.

@@            Coverage Diff             @@
##             main    #1610      +/-   ##
==========================================
+ Coverage   86.25%   86.41%   +0.16%     
==========================================
  Files          58       58              
  Lines        4771     4761      -10     
  Branches      801      798       -3     
==========================================
- Hits         4115     4114       -1     
+ Misses        465      456       -9     
  Partials      191      191              

Impacted Files	Coverage Δ
singer_sdk/mapper_base.py	54.71% <0.00%> (-1.43%)	⬇️
singer_sdk/tap_base.py	71.56% <0.00%> (+2.47%)	⬆️
singer_sdk/plugin_base.py	85.89% <61.53%> (-2.30%)	⬇️
singer_sdk/target_base.py	87.83% <100.00%> (+1.69%)	⬆️

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