The Brazilian ABNT2 Keyboard layout contains a keypad
decimal key which doesn't exist on other keypads:-
https://www.kbdlayout.info/kbdbr/virtualkeys
This key is curently mapped in xorgxrdp to keycode 134 (basic mapping),
but isn't present in the scancode map. It needs to be added so that it
is available to VNC sessions and will be mapped for xorgxrdp when we
move to evdev keycode mappings.
The mapping from scancodes to the indexes used in xrdp_keymap
is not well designed and contains an implicit dependency on
keycode values.
This mapping is alse slightly different from the index used for
the 'keys' map in the xrdp_wm structure.
This commit introduces support for mapping scancodes directly
to 'scancode indexes' suitable for indexing into both structures.
Some renaming is also done; [MS-RDPBCGR] uses the terms scancode
and keyCode interchangeably. An effort is made to use key_code for a
raw value from a TS_KEYBOARD_EVENT, and scancode for a value which is
produced by the scancode module.
