Add default syslog server

[aphralG]

Proposed changes

Added syslog server port option in agent config

syslog_server:
    port: 1514

Default value is 1514, agent will parse the NGINX config for Nap syslog server directives, when one is found agent will check if the host is valid and then check if the port matches the configured syslog server port in the config (or default if not set)
If the agent fails to find a valid syslog server it will log the following warning, which contains the configured port

level=WARN msg="Could not find available local NGINX App Protect syslog server configured on port 565. Security violations will not be collected."

Changed NapSyslogServers in NginxConfigContext to a single value as we no longer allow multiple syslog servers.

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

[codecov]

Codecov Report

❌ Patch coverage is 93.61702% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 86.41%. Comparing base (61f1fc8) to head (af10ba7).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
internal/collector/otel_collector_plugin.go	91.30%	1 Missing and 1 partial ⚠️
internal/model/config.go	0.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1317      +/-   ##
==========================================
+ Coverage   86.29%   86.41%   +0.12%     
==========================================
  Files         102      102              
  Lines       12580    12590      +10     
==========================================
+ Hits        10856    10880      +24     
+ Misses       1248     1232      -16     
- Partials      476      478       +2     

Files with missing lines	Coverage Δ
internal/config/config.go	87.23% <100.00%> (+0.10%)	⬆️
internal/config/defaults.go	100.00% <ø> (ø)
internal/config/flags.go	100.00% <ø> (ø)
internal/config/types.go	86.04% <ø> (ø)
internal/datasource/config/nginx_config_parser.go	78.69% <100.00%> (-0.20%)	⬇️
internal/model/config.go	90.47% <0.00%> (ø)
internal/collector/otel_collector_plugin.go	82.54% <91.30%> (+0.03%)	⬆️

... and 5 files with indirect coverage changes

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