`/debugtypemap`, possibly a Lua texture

Add some way to visualize the typemap.

Perhaps it could be texture accessible to Lua for editors, see gajop's old request for SpringBoard https://springrts.com/mantis/view.php?id=5692

Start by locating the existing `/debugtypemap` entry point and typemap handling in RecoilEngine, then read the linked SpringBoard request for context. Done means the typemap can be visualized, potentially through a texture accessible to Lua editors; the issue does not identify specific files or tests.

Written by the indexing model from the issue text.