Add a z64play.h header (#1646)

* z64play.h

* Move macros, functions and variables to header

* cleanup

* Reduce needed headers on z_collision_check

* Change play functions to take PlayState

* Move `Actor_ProcessInitChain` to `ichain.h`

* format

* Update src/code/z_play.c

Co-authored-by: Derek Hensley <hensley.derek58@gmail.com>

* Add macros.h to sys_math3d.c

* Rename SequenceContext to SceneSequences

---------

Co-authored-by: Derek Hensley <hensley.derek58@gmail.com>

src/code/sys_math3d.c

@@ -38,11 +38,11 @@ struct Dummy227 { int x; };
 #include "PR/gu.h"
 // The bss index at this point should be 184
 
+#include "macros.h"
+
 Vec3f gZeroVec3f = { 0.0f, 0.0f, 0.0f };
 Vec3s gZeroVec3s = { 0, 0, 0 };
 
-#define ARRAY_COUNT(arr) (s32)(sizeof(arr) / sizeof(arr[0]))
-
 f32 Math3D_Normalize(Vec3f* vec) {
     f32 magnitude = Math3D_Vec3fMagnitude(vec);