Parse gRPC/HTTP2 requests with kprobes

[grcevski]

This PR brings support for tracking grpc and http2 requests for non-go languages. It parses a bit of the information at eBPF time and it send the actual header decoding to be done in user space.

There are few things missing from this draft:

• We don't read the status code yet, I need to figure out how to do that
• No integration tests

I'm mainly making the PR so I can see if the tests pass or if I've broken some of the HTTP support.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 80.70175% with 33 lines in your changes are missing coverage. Please review.

Project coverage is 79.18%. Comparing base (490e84f) to head (15f1f5b).

Files	Patch %	Lines
pkg/internal/ebpf/common/http2grpc_transform.go	80.47%	27 Missing and 6 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #649      +/-   ##
==========================================
- Coverage   79.23%   79.18%   -0.05%     
==========================================
  Files          91       92       +1     
  Lines        7575     7746     +171     
==========================================
+ Hits         6002     6134     +132     
- Misses       1246     1277      +31     
- Partials      327      335       +8     

Flag	Coverage Δ
integration-test	70.39% <80.70%> (+0.22%)	⬆️
unittests	40.22% <0.00%> (-1.06%)	⬇️

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[grcevski]

I added some grpc tests, I'm going to add HTTP2 tests with our rust ssl server. I can't use the go http2 tests because we don't decode go ssl without go probes support.

[mariomac]

Amazing

[grcevski]

Thanks Mario!