Updates all directional keys to use WASD as defaults

[nickfloyd]

Fixes: https://github.com/katharostech/skipngo/issues/33

We want to default the up, left, down, and right movement keys to the more common WASD until a more extensible configuration solution can be built.

Acceptance Criteria:

• [x] When pressing W the character moves up
• [x] When pressing A the character moves left
• [x] When pressing S the character moves down
• [x] When pressing D the character moves right
• [x] When pressing up arrow the character moves up
• [x] When pressing left arrow the character moves left
• [x] When pressing down arrow the character moves down
• [x] When pressing right arrow the character moves right

VALIDATION

1. Checkout this branch: change-directional-keys
2. cargo run -- --asset-dir [LOCATION of your assets with an in gamer character that uses movement]
3. Verify that W, A, S, D moves the character as expected

NOTES

• We had some discussion around some configuration approaches that would work well but those will be a future concern.
• Additionally I was thinking that we'd make this change to encapsulate up arrow || W but that just seemed to introduce unnecessary complexity that was going to be replaced by a future config feature.
• This may need to be reconsidered for modified keyboard layouts and non-US layouts - though that can easily be an AC of the configuration work.