This PR aims to reduce the very cluttersome registration of keybinds in the MegamekController. It does this by adding a few more registration methods, mainly one that requires the KeyBind, a KeyBindReceiver (an interface with a single method, shouldReceiveKeyCommands) and a performer method that acts on a keybind.

The thought is that the shouldReceiveKeyCommands() method is often very repetitive and can even be inherited (as is done for most of the StatusBarPhaseDisplays now). The performer method is often already present and just has to be named as a method reference, or it can be created.

This transforms this call:

        controller.registerCommandAction(KeyCommandBind.FIRE.cmd,
                new CommandAction() {

                    @Override
                    public boolean shouldPerformAction() {
                        if (!clientgui.getClient().isMyTurn()
                                || clientgui.getBoardView().getChatterBoxActive()
                                || !display.isVisible()
                                || display.isIgnoringEvents()
                                || !buttons.get(FiringCommand.FIRE_FIRE).isEnabled()) {
                            return false;
                        } else {
                            return true;
                        }
                    }

                    @Override
                    public void performAction() {
                        fire();
                    }
                });

into this:

controller.registerCommandAction(KeyCommandBind.FIRE, this::shouldPerformFireKeyCommand, this::fire);

This line is not immediately clear all by itself. I believe I've given it ample javadoc to be read upon hovering it.

This PR also changes the CommandAction class to interface and removes the hasReleaseAction() method. Instead, the release action is always called on a keybind key release, it just does nothing by default. I had no intention of making any noticeable changes to the keybinds and I have not tried to simplify the code in some of the performers although one probably could.