Support dynamic frame size

[fwcd]

Updating the window resize currently scales the entire HUD, sometimes pushing GUI elements out of the window's bounds. The PR aims to fix this by no longer assuming a constant (logical) frame size and adding the appropriate handlers for dynamically updating the HUD nodes' positions (and sizes).

• Add FrameSizeDependent protocol for adoption by components responsible for managing a (HUD) entity's position and size
• Update HUD elements with components implementing FrameSizeDependent:
  • Debug HUD
  • Crosshair HUD
  • Hotbar HUD
  • Pause HUD (in progress, slightly trickier due to requiring a resize of the background overlay, which is not entirely straightforward without recreating the SKShapeNode)
  • Achievement HUD
  • Control Pad HUD (iOS only)