Better HTTP/SMTP Multipart parsing

[roxblnfk]

What was changed

Fix parsing for multipart/mixed data when:

• There is trailing dot (.) in raw data. In this case connection was frozen.
• A multipart field doesn't contain Content-Disposition header. In this case parser just failed and zero chunks was parsed.

Related with buggregator/server#213

[codecov]

Codecov Report

Attention: Patch coverage is 58.82353% with 14 lines in your changes missing coverage. Please review.

Project coverage is 22.72%. Comparing base (da9a205) to head (4ed68e0).

Files	Patch %	Lines
src/Traffic/Parser/MultipartType.php	0.00%	14 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master     buggregator/frontend#128      +/-   ##
============================================
+ Coverage     22.70%   22.72%   +0.02%     
- Complexity     1333     1335       +2     
============================================
  Files           156      157       +1     
  Lines          4158     4176      +18     
============================================
+ Hits            944      949       +5     
- Misses         3214     3227      +13     

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