Implement the jetpack tool

[trundlr]

Jetpack will be a good tool to implement as it will challenge the way we handle input.

• Currently, the player controller uses W/S for aim and A/D for movement.
• When a jetpack is equipped, a grub should be able to move with WASD through the air. Gravity should still affect them.
• A jetpack has a charge that runs out while W is held down
• The jetpack charge is shown clearly to all players

The jetpack should largely be art-ready. We will have to add a few particles and sound post implementation.

[ShadowBrian]

I got most of this done except for the charge level- needs UI work

[matekdev]

Finished except for one issue that I currently have assigned to myself.