Foundation to report application processes

[mariomac]

This PR provides the foundation for reporting application processes.

It currently only reports the OTEL standard process.cpu.utilization metric, but the PR is big and complex enough to leave the following missing functionalities for future, smaller PRs:

• Report CPU metrics per user/system/wait state.
• Report the rest of metrics here https://opentelemetry.io/docs/specs/semconv/system/process-metrics/
• Decorate the process metrics with application metadata (service/ns name, k8s metadata, etc...)
• Cleanup a bit the imported code from NR
• Prometheus exporter/filter/expirer

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 55.12367% with 254 lines in your changes missing coverage. Please review.

Project coverage is 71.64%. Comparing base (294a8d9) to head (2833a13).

Files	Patch %	Lines
pkg/internal/export/otel/metrics_proc.go	0.00%	75 Missing ⚠️
pkg/internal/infraolly/process/snapshot.go	66.85%	44 Missing and 16 partials ⚠️
pkg/internal/infraolly/process/collect.go	0.00%	44 Missing ⚠️
pkg/internal/infraolly/process/status.go	12.50%	28 Missing ⚠️
pkg/internal/pipe/proc_pipeline.go	30.00%	21 Missing ⚠️
pkg/internal/infraolly/process/harvest.go	78.37%	8 Missing and 8 partials ⚠️
pkg/internal/export/otel/common.go	66.66%	3 Missing and 1 partial ⚠️
pkg/internal/export/otel/metrics.go	66.66%	3 Missing and 1 partial ⚠️
pkg/internal/ebpf/common/pids.go	0.00%	1 Missing ⚠️
pkg/internal/netolly/ebpf/record_getters.go	95.23%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #892      +/-   ##
==========================================
- Coverage   77.87%   71.64%   -6.24%     
==========================================
  Files         126      132       +6     
  Lines        9136     9620     +484     
==========================================
- Hits         7115     6892     -223     
- Misses       1551     2253     +702     
- Partials      470      475       +5     

Flag	Coverage Δ
integration-test	?
k8s-integration-test	56.40% <21.90%> (-2.33%)	⬇️
oats-test	35.47% <9.54%> (-1.51%)	⬇️
unittests	43.92% <54.24%> (+0.27%)	⬆️

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[grcevski]

LGTM! Awesome!