Disable mandatory TLS verification with --insecure

[d4xfe]

getpeercert() only returns the certificate with enabled certificate validation. Because of this, I updated it to getpeercert(True), which will return a binary blob of the servers certificate regardless of the verification mode.

I added the util method cert_der_to_dict using ssl internals to convert the blob to a python dict like getpeercert() would.
The flag --insecure was introduced to disable certificate validation of ssl sockets.
This allows TLS interception when the server is using a self-signed certificate.

This is my first pull request on GitHub and I'm still a bit confused. So if I should change anything let me know.

[abhinavsingh]

@d4xfe Thank you, looks excellent considering this is your first PR. Congratulations.

Can you please:

1. Resolve conflicts
2. Sync your branch with develop. For some reasons, I see diffs in your PR which are not part of your changes

[d4xfe]

@abhinavsingh Thanks. I've synced the branches and I don't conflicts anymore.

[codecov]

Codecov Report

Attention: Patch coverage is 87.09677% with 4 lines in your changes missing coverage. Please review.

Project coverage is 84.37%. Comparing base (39854e1) to head (ec87033).
Report is 21 commits behind head on develop.

Files with missing lines	Patch %	Lines
proxy/common/utils.py	81.81%	1 Missing and 1 partial ⚠️
proxy/core/connection/server.py	33.33%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1401      +/-   ##
===========================================
- Coverage    84.57%   84.37%   -0.20%     
===========================================
  Files          177      178       +1     
  Lines         8103     8130      +27     
  Branches      1239     1242       +3     
===========================================
+ Hits          6853     6860       +7     
- Misses        1052     1059       +7     
- Partials       198      211      +13     

Flag	Coverage Δ
GHA	84.36% <87.09%> (-0.05%)	⬇️
Linux	83.99% <87.09%> (-0.04%)	⬇️
Python 3.10	85.13% <82.60%> (-0.02%)	⬇️
Python 3.11	84.31% <87.09%> (+<0.01%)	⬆️
Python 3.12	79.36% <87.09%> (-4.96%)	⬇️
Python 3.6	?
Python 3.7	?
Python 3.8	?
Python 3.9	85.21% <82.60%> (-0.02%)	⬇️
Windows	?
macOS	84.36% <87.09%> (-0.05%)	⬇️
pytest	84.36% <87.09%> (-0.05%)	⬇️

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[abhinavsingh]

@d4xfe Thank you for this work and the PR. There are some workflow issues. I am going create a new PR based on top of your contribution and try to this ship.