Add cli flags for various viewer settings

[ExcaliburZero]

Related to #65

Adds command line flags for the view subcommand to allow the user to configure the following settings that were previously hard-coded constants:

• Window width and height (--window-width and --window-height)
• Animation playback speed (--animation-fps)
• Background color (--bg-color)

apicula.exe view \
    --window-width 1000 \
    --window-height 800 \
    --animation-fps 30 \
    --bg-color "#00ff00" \
    *

[scurest]

I'm not really interested in adding this. It doesn't seem that important to me for the user to be able to change these.

Also I haven't worked on this in a long time and am not likely to merge PRs.

[ExcaliburZero]

Understandable.

Thank you for your time!