Add engine extension checks at VM startup and a nudgeoutofsolid fallback

Add engine extension checks at VM startup and a nudgeoutofsolid fallback

This allows printing proper messages immediately rather than crashing
later or silently failing to download maps or support player IDs, which
may prevent broken 3rd party packages.

Implements a fallback to WarpZoneLib_MoveOutOfSolid() for when the new
DP_QC_NUDGEOUTOFSOLID isn't available.  Adds a "wasn't-stuck" `-1`
result to WarpZoneLib_MoveOutOfSolid(), to prevent warning spam in the
fallback path.