Added cgo profile to build NGINX Agent packages

[oliveromahony]

Proposed changes

Since go 1.20 https://go.dev/doc/pgo was introduced.
Added cgo production profile to build NGINX Agent packages. This reduces the CPU usage of the NGINX Agent from 4 - 9% 3 - 6%. Config Apply 17% -> 9% anecdotally. However, It does increase the package size. This is a tradeoff.

Enable #422

curl -s http://localhost:6060/debug/pprof/profile > ./cpu.out
mv profile.cgo profile.prof
go tool pprof -proto cpu.out profile.prof > profile.cgo
rm profile.prof cpu.out

Checklist

Before creating a PR, run through this checklist and mark each as complete.

• I have read the CONTRIBUTING document
• I have run make install-tools and have attached any dependency changes to this pull request
• If applicable, I have added tests that prove my fix is effective or that my feature works
• If applicable, I have checked that any relevant tests pass after adding my changes
• If applicable, I have updated any relevant documentation (README.md)
• If applicable, I have tested my cross-platform changes on Ubuntu 22, Redhat 8, SUSE 15 and FreeBSD 13

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[codecov-commenter]

Codecov Report

Patch coverage has no change and project coverage change: -0.51% ⚠️

Comparison is base (04748e8) 66.72% compared to head (4f7d114) 66.22%.
Report is 3 commits behind head on main.

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Additional details and impacted files

@@            Coverage Diff             @@
##             main     #472      +/-   ##
==========================================
- Coverage   66.72%   66.22%   -0.51%     
==========================================
  Files         114      118       +4     
  Lines       12951    13274     +323     
==========================================
+ Hits         8642     8791     +149     
- Misses       3736     3900     +164     
- Partials      573      583      +10     

Files Changed	Coverage Δ
...or/github.com/nginx/agent/sdk/v2/config_helpers.go	64.19% <ø> (ø)

... and 13 files with indirect coverage changes

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