modorganizer-bsa_extractor

This change adds generic game-feature archive dispatch to bsa_extractor.

Maintainer Notes

• New feature shape: MOBase::GameArchiveHandler
  • supportedArchiveNameFilters()
  • supportsArchive(path)
  • extractArchive(path, outputDirectory, progress, errorMessage)
  • optional canCreateArchive(path) / createArchive(...)
• Dispatch behavior:
  • ask the active game for GameArchiveHandler
  • delegate when the feature exists and claims the archive
  • otherwise use the existing bsatk .bsa / .ba2 fallback unchanged
• Availability:
  • the plugin remains visible for now
  • unsupported games still behave gracefully because the plugin only acts when it finds candidate archives, and non-delegated .bsa / .ba2 files still follow the existing bsatk path
• Progress callback:
  • delegated extraction now follows the canonical uibase progress callback std::function<void(qint64 current, qint64 total)>
  • the delegated progress dialog therefore shows archive-level progress instead of per-file names; bsatk extraction keeps its existing filename detail

Companion game-plugin work is still required for any non-bsatk format: the game plugin must register GameArchiveHandler through MO2 game features.

This branch now expects the canonical uibase GameArchiveHandler API to be available.