added option to control body parsing

[olegbaturin]

Q	A
Is bugfix?	❌
New feature?	✔️
Breaks BC?	❌

Example for #65

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 33.33333% with 10 lines in your changes missing coverage. Please review.

Project coverage is 92.48%. Comparing base (5d18903) to head (b62935b). Report is 11 commits behind head on master.

Files with missing lines	Patch %	Lines
src/CsrfMiddleware.php	45.45%	6 Missing :warning:
src/EmptyCsrfToken.php	0.00%	4 Missing :warning:

Additional details and impacted files

@@              Coverage Diff              @@
##              master      #66      +/-   ##
=============================================
- Coverage     100.00%   92.48%   -7.52%     
- Complexity        47       52       +5     
=============================================
  Files              8        9       +1     
  Lines            128      133       +5     
=============================================
- Hits             128      123       -5     
- Misses             0       10      +10     

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[samdark]

See discussion at https://github.com/yiisoft/csrf/issues/65#issuecomment-2120529851