fix: Clock runs game simulation too fast sometimes when limiting fps

[eonarheim]

===:clipboard: PR Checklist :clipboard:===

• 📌 issue exists in github for these changes
• 🔬 existing tests still pass
• 🙈 code conforms to the style guide
• 📐 new tests written and passing / old tests updated with new scenario(s)
• 📄 changelog entry added (or not needed)

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This PR fixes an unreleased issue where sometimes when constraining fps with the clock, the update loop would get out of phase and the elapsed time passed to the mainloop could be nearly double the fps. Ironically the clock loops were running correctly, the elapsed time passed to the simulation was wrong.

Changes:

• Refactored the update to be a little easier to read
• Shifts the update elapsed time to be in-phase with the fps, the loop still counts updates correctly to match fps