bpo-46008: Make runtime-global object/type lifecycle functions and state consistent. (gh-29998)

This change is strictly renames and moving code around.  It helps in the following ways:

* ensures type-related init functions focus strictly on one of the three aspects (state, objects, types)
* passes in PyInterpreterState * to all those functions, simplifying work on moving types/objects/state to the interpreter
* consistent naming conventions help make what's going on more clear
* keeping API related to a type in the corresponding header file makes it more obvious where to look for it

https://bugs.python.org/issue46008

Include/internal/pycore_floatobject.h

@@ -8,6 +8,35 @@ extern "C" {
 #  error "this header requires Py_BUILD_CORE define"
 #endif
 
+
+/* runtime lifecycle */
+
+extern void _PyFloat_InitState(PyInterpreterState *);
+extern PyStatus _PyFloat_InitTypes(PyInterpreterState *);
+extern void _PyFloat_Fini(PyInterpreterState *);
+
+
+/* other API */
+
+#ifndef WITH_FREELISTS
+// without freelists
+#  define PyFloat_MAXFREELIST 0
+#endif
+
+#ifndef PyFloat_MAXFREELIST
+#  define PyFloat_MAXFREELIST   100
+#endif
+
+struct _Py_float_state {
+#if PyFloat_MAXFREELIST > 0
+    /* Special free list
+       free_list is a singly-linked list of available PyFloatObjects,
+       linked via abuse of their ob_type members. */
+    int numfree;
+    PyFloatObject *free_list;
+#endif
+};
+
 /* _PyFloat_{Pack,Unpack}{4,8}
  *
  * The struct and pickle (at least) modules need an efficient platform-