ENG ideas: Change Respected Game Type Without Invalidating Withdrawals

We wanted to share an idea for some teams to explore about creating "Change Respected Game Type Without Invalidating Withdrawals"

**Is your feature request related to a problem? Please describe.**

When the respected game type is changed in OptimismPortal, it also invalidates any already proven withdrawals, requiring users to reprove them and wait an additional 7 days. While this is desirable in some cases, we need a way to change the respected game type without invalidating withdrawals. This avoids users being impacted when pre-emptively switching to the permissioned game or when switching back to the permissionless game after fixes are deployed.

**Additional context**

We would like to start this line of work in H2 2024.

Start by reviewing OptimismPortal's respected game type changes and how they affect already proven withdrawals. Done means supporting a game-type change without invalidating those withdrawals, including switches to the permissioned game and back to the permissionless game.

Written by the indexing model from the issue text.