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 https://github.com/buggregator/server/issues/213

[codecov[bot]]

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 :warning:

Additional details and impacted files

```diff @@ 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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