feat: auditlog syslog writer

[Serjick]

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Summary:
Implementation of plugintypes.AuditLogWriter to send audit logs into syslog. Stdlib log/syslog package has been used, so no extra dependencies needed.
Writes directed into local0 syslog facility with LOG_INFO severity by default. Interrupted transactions will have LOG_ERR severity.

Changes:
SecAuditLogType directive now accept syslog value.
SecAuditLog directive now accept all supported by log/syslog values of network and raddr by pattern network://raddr (e.g. udp://127.0.0.1:514, unixgram:///var/run/syslog). Empty value will force log/syslog to select destination by it's internal logic.

Limitations:
Not available for tinygo because of not verified log/syslog support.
Not available for windows and plan9 operating systems because of log/syslog limitations.

Thanks for your contribution ❤️

[codecov]

Codecov Report

Attention: Patch coverage is 67.44186% with 14 lines in your changes missing coverage. Please review.

Project coverage is 84.27%. Comparing base (d0ca474) to head (d1e6583).

Files with missing lines	Patch %	Lines
internal/auditlog/syslog_writer.go	70.27%	8 Missing and 3 partials ⚠️
internal/auditlog/init_tinygo.go	0.00%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1383      +/-   ##
==========================================
- Coverage   84.34%   84.27%   -0.08%     
==========================================
  Files         170      171       +1     
  Lines        9933     9976      +43     
==========================================
+ Hits         8378     8407      +29     
- Misses       1310     1320      +10     
- Partials      245      249       +4     

Flag	Coverage Δ
coraza.rule.case_sensitive_args_keys	84.23% <67.44%> (-0.08%)	⬇️
coraza.rule.multiphase_evaluation	83.93% <67.44%> (-0.08%)	⬇️
coraza.rule.no_regex_multiline	84.21% <67.44%> (-0.08%)	⬇️
default	84.27% <67.44%> (-0.08%)	⬇️
examples+	16.25% <0.00%> (-0.08%)	⬇️
examples+coraza.rule.case_sensitive_args_keys	84.23% <67.44%> (-0.08%)	⬇️
examples+coraza.rule.multiphase_evaluation	83.77% <67.44%> (-0.08%)	⬇️
examples+coraza.rule.no_regex_multiline	84.13% <67.44%> (-0.08%)	⬇️
examples+memoize_builders	84.24% <72.50%> (-0.08%)	⬇️
examples+no_fs_access	81.62% <67.44%> (-0.07%)	⬇️
ftw	84.27% <67.44%> (-0.08%)	⬇️
memoize_builders	84.37% <72.50%> (-0.08%)	⬇️
no_fs_access	83.77% <67.44%> (-0.08%)	⬇️
tinygo	84.24% <67.44%> (-0.08%)	⬇️

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