Keymap: expose tool keymaps in the preferences

Currently some modes share tool keymaps, we might want to disable
this since it's confusing editing one thing in multiple places.

However this should be resolved in the tool definitions.

tests/python/bl_keymap_completeness.py

@@ -27,12 +27,12 @@ from bpy_extras import keyconfig_utils
 def check_maps():
     maps = {}
 
-    def fill_maps(ls):
-        for km_name, km_space_type, km_region_type, km_sub in ls:
+    def fill_maps(seq):
+        for km_name, km_space_type, km_region_type, km_sub in seq:
             maps[km_name] = (km_space_type, km_region_type)
             fill_maps(km_sub)
 
-    fill_maps(keyconfig_utils.KM_HIERARCHY)
+    fill_maps(keyconfig_utils.km_hierarchy())
 
     import bpy
     keyconf = bpy.context.window_manager.keyconfigs.active