SecretsManager: list_secrets() now filters values with special chars correctly

[bblommers]

Followup to #8469, words are now also split by special characters (/, +, and a few others).

Fixes #8421

Whether this is the final form of this algorithm, I don't know - it's quite possible that I've missed some use cases. It is currently closer to AWS parity than before though, with the (AWS-validated) tests to prove it.

[codecov]

Codecov Report

Attention: Patch coverage is 95.45455% with 1 line in your changes missing coverage. Please review.

Project coverage is 92.63%. Comparing base (69a3669) to head (ad4d632).
Report is 8 commits behind head on master.

Files with missing lines	Patch %	Lines
moto/secretsmanager/list_secrets/filters.py	95.45%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #8529      +/-   ##
==========================================
- Coverage   92.63%   92.63%   -0.01%     
==========================================
  Files        1224     1229       +5     
  Lines      105980   106414     +434     
==========================================
+ Hits        98170    98572     +402     
- Misses       7810     7842      +32     

Flag	Coverage Δ
servertests	27.92% <81.81%> (+0.17%)	⬆️
unittests	92.60% <95.45%> (+<0.01%)	⬆️

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