[Feature] Rewrite rspamd_stats.pl and mapstats.pl as rspamadm Lua subcommands

[Feature] Rewrite rspamd_stats.pl and mapstats.pl as rspamadm Lua subcommands

Add rspamadm logstats and rspamadm mapstats commands that replace the
Perl utility scripts utils/rspamd_stats.pl and utils/mapstats.pl.

- lua_log_utils.lua: shared library for log format detection, timestamp
  conversion, compressed file handling, directory scanning, and progress
  spinner
- logstats.lua: full port of rspamd_stats.pl with all options including
  symbol filtering, bidirectional symbols, groups, correlations, score
  multipliers, time range filtering, and JSON output via UCL
- mapstats.lua: full port of mapstats.pl using native rspamd_config for
  multimap access, rspamd_regexp for regex maps with full flag support,
  and rspamd_ip for IP/CIDR matching (no external dependencies)