Added arrow shower combat skill for archer player

[dschipor]

The player can shoot a rain of arrows that damage all enemies in a certain area. The player can aim using the mouse.

Effect: https://gfycat.com/yawningpalatableaustraliancurlew

Logic:

• Get AOE area center using raycast on environment layer mask objects
• Check for colliders on enemy layer mask with physics overlap box (given skill height and radius; height is required in order to hit enemies such as birds)
• Check if found colliders are within the AOE cylinder volume
• Apply damage to enemies for specific value / rate / duration