ref(grouping): refactoring parametrization

[vartec]

Pulling out parametrization logic out of grouping.strategies.message and making it more reusable:

• regex split into individual composable components;
• using regex lookbehind instead of adding and removing = hack
• refactored experiments;

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 95.12195% with 6 lines in your changes are missing coverage. Please review.

Project coverage is 77.91%. Comparing base (de3bca4) to head (5825b8b). Report is 78 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #71078      +/-   ##
==========================================
+ Coverage   73.96%   77.91%   +3.95%     
==========================================
  Files        6532     6525       -7     
  Lines      291114   290544     -570     
  Branches    50376    50286      -90     
==========================================
+ Hits       215311   226372   +11061     
+ Misses      69320    57915   -11405     
+ Partials     6483     6257     -226     

Files	Coverage Δ
src/sentry/grouping/strategies/message.py	97.14% <90.00%> (+1.39%)	:arrow_up:
src/sentry/grouping/parameterization.py	95.57% <95.57%> (ø)

... and 918 files with indirect coverage changes