Keymap: continued testing/development

After testing in the studio and extending the event system for
drag events, we've agreed on adjustments to the new keymap,
see: T55162

- Tab: Edit-mode toggle.
- Tab + Cursor Drag: mode switching pie menu.
- Accent/Grave: for 3D view pie menu.
- F3: Search
- 1..3, Shift-1..3: Edit mesh vertex/edge/face toggle.

Other minor changes were made, however they aren't part of the design.

- Ctrl-Shift-S: Image editor Save-As (was F3)
- Ctrl-Alt-R: Repeat history (was F3)

source/blender/windowmanager/intern/wm_operators.c

@@ -3989,7 +3989,7 @@ void wm_window_keymap(wmKeyConfig *keyconf)
 
 	/* menus that can be accessed anywhere in blender */
 
-	WM_keymap_verify_item(keymap, "WM_OT_search_menu", TABKEY, KM_PRESS, 0, 0);
+	WM_keymap_verify_item(keymap, "WM_OT_search_menu", F3KEY, KM_PRESS, 0, 0);
 
 #ifdef WITH_INPUT_NDOF
 	WM_keymap_add_menu(keymap, "USERPREF_MT_ndof_settings", NDOF_BUTTON_MENU, KM_PRESS, 0, 0);