Set a limit on the number of access logs Agent can tail

[spencerugbo]

Proposed changes

Limit the number of access logs that Agent tails by default in order to reduce overhead. The limit can be configured in the agent conf as seen in the following example:

log:
  # set log level (error, warn, info, debug; default "info")
  level: info
  # set log path. if empty, don't log to file.
  path: /var/log/nginx-agent/

allowed_directories: 
    - /etc/nginx
    - /etc/app_protect
    - /usr/local/etc/nginx
    - /usr/share/nginx/modules
    - /var/run/nginx
    - /var/log/nginx

data_plane_config:
    nginx:
        # set the max access log files to be watched (default 10)
        max_access_log_files: 5

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

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 85.29%. Comparing base (db165d2) to head (7e3379e).
⚠️ Report is 9 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1418      +/-   ##
==========================================
- Coverage   86.27%   85.29%   -0.98%     
==========================================
  Files         102      102              
  Lines       12622    12938     +316     
==========================================
+ Hits        10890    11036     +146     
- Misses       1253     1416     +163     
- Partials      479      486       +7     

Files with missing lines	Coverage Δ
internal/config/config.go	87.44% <100.00%> (+0.14%)	⬆️
internal/config/defaults.go	100.00% <ø> (ø)
internal/config/flags.go	100.00% <ø> (ø)
internal/config/types.go	87.65% <ø> (ø)
internal/datasource/config/nginx_config_parser.go	78.85% <100.00%> (+0.16%)	⬆️

... and 16 files with indirect coverage changes

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