Also removes a bunch of old implementations of pad locking and
filtering which are no longer needed. (They're now handled by the
uniform locking code.)
Also removes some of the auto-promotion logic. Rotating a footprint
when a pad was selected is going to be surprising whether the pad
is locked or not.
Fixes https://gitlab.com/kicad/code/kicad/issues/8322
SHIFT, CTRL, ALT modifier keys were handled in 2 different codes, one for
the selection tool and another to modify the mouse cursor shape, with 2
different configs.
Now the modifiers are managed from only one function.
Pcbnew: group also SHIFT, CTRL, ALT modifier keys management to a specific function.
Fixes#8021https://gitlab.com/kicad/code/kicad/issues/8021