Moves the seven proprietary-data-tree handlers out of main.cpp:
--migrate-data-tree --bench-migrate-data-tree
--list-data-tree-largest --export-data-tree-md
--info-data-tree --strip-data-tree
--audit-data-tree
All operate on a Blizzard-format extracted Data tree (the .m2/
.skin/.wmo/.blp/.dbc files) — they audit, migrate, or strip
proprietary-format files in support of the open-format
migration story.
Original placement spanned two sub-blocks (12546-12892 and
13093-13417 in main.cpp) interrupted by --gen-texture and
--add-texture-to-zone in the middle. Extraction collapses
both sub-blocks into one cohesive translation unit.
main.cpp drops 16,321 → 15,653 lines (-668). Behavior verified
by re-running --info-data-tree against a missing directory.
