Fix left click targeting issue

[NickAragua]

Fixes #2819

The first commit is coalescing the drag and click handling into doing the same thing, as the "drag" functionality in these displays didn't seem to be doing anything at all.

The second commit is cleaning up unused variables and enabling the user to flip arms without resetting torso twist state (technically it's a push/pop, but details).

[Windchild292]

Looks mostly good, just two comments first

[Windchild292]

Why remove this check? I did note it wasn't part of the other ones though

[NickAragua]

Restored.

[HoneySkull]

I found the root cause as to why using the BUTTON1_DOWN_MASK behaves differently than the original BUTTON1_MASK.
With the deprecated getModifiers() method, the mask is set for button 1 on both the mouse down and mouse release. With the updated getModifiersEx() the BUTTON1_DOWN_MASK is set on the mouse down but is NOT set on the mouse release.

For example FireDisplay.java and others implement this check to bail if not mouse button 1:

    // ignore buttons other than 1
    if (!clientgui.getClient().isMyTurn()
        || ((b.getModifiers() & InputEvent.BUTTON1_DOWN_MASK) == 0)) {
        return;
    }```

This used to work fine, but now, on mouseReleased() will always look like the button1 was not used and will therefore exit before doing it's left-click payload such as selecting the hex for target.

To properly fix this, BoardViewEvent that is passed into board listeners hexMouse() functions needs to carry the mouse event button clicked from the mouse event along with the mask.

I believe, if I fix this properly, the "flip/twist" functionality can be restored correctly if desired.

[HoneySkull]

For example, if the user presses button 1 followed by button 2, and then releases them in the same order, the following sequence of events is generated:

MOUSE_PRESSED: BUTTON1_DOWN_MASK
MOUSE_PRESSED: BUTTON1_DOWN_MASK | BUTTON2_DOWN_MASK
MOUSE_RELEASED: BUTTON2_DOWN_MASK
MOUSE_CLICKED: BUTTON2_DOWN_MASK
MOUSE_RELEASED:
MOUSE_CLICKED:

//note the mask modifiers for the releases are 0 for the button being released.