decomp3: spawn target, add merc and particle buckets and some temporary hacks (#3445)

This includes all the collision stuff needed to spawn `target`,
decompiles the sparticle code and adds some of the PC hacks needed for
merc to run (it doesn't work quite right and looks bad, likely due to a
combination of code copied from Jak 2 and the time of day hacks).

There are a bunch of temporary hacks (see commits) in place to prevent
the game from crashing quite as much, but it is still extremely prone to
doing so due to lots of missing functions/potentially bad decomp.

---------

Co-authored-by: water <awaterford111445@gmail.com>

common/util/string_util.cpp

@@ -247,7 +247,7 @@ std::string titlize(const std::string& str) {
 }
 
 std::string pad_right(const std::string& input, const int width, const char padding_char) {
-  if (input.length() >= width) {
+  if ((int)input.length() >= width) {
     return input;  // No need to pad if input length is already greater or equal to width
   } else {
     int padding_width = width - input.length();