[jak2] More texture animations (#2831)

Added framework to do texture animations entirely in C++. Currently only
works on relatively simple ones, and doesn't handle updating all
parameters - only the speeds.

Connected texture animations to merc and tfrag for skull gems, dark
bomb, and scrolling conveyors.

Cleaned up Tfragment/Tfrag3, which used to be two classes. This was one
of the first C++ renderers, so it had a weird design.

common/texture/texture_slots.cpp

@@ -22,6 +22,12 @@ std::vector<std::string> jak2_slots = {
     //"kor-head-formorph-noreflect",
     //"kor-lowercaps-formorph",
     //"kor-uppercaps-formorph",
+    "skull-gem-dest",
+    "bomb-gradient",
+    "cas-conveyor-dest",
+    "cas-conveyor-dest-01",
+    "cas-conveyor-dest-02",
+    "cas-conveyor-dest-03",
 };
 
 }