feat(forge): cheat that starts or changes the prank

[PaulRBerg]

Component

Forge

Describe the feature you would like

I use the changePrank added in foundry-rs/forge-std#319 a lot, and one of the issues I have with it is that I always need to ensure that it's called after a vm.startPrank. Otherwise, Foundry throws this error:

You have an active prank already.

Users would never see this error if there was a cheat that combined startPrank and changePrank like this:

• Is prank started?
  • If not, run vm.startPrank
  • If yes, replicate the logic in changePrank (i.e. vm.stopPrank and vm.startPrank again)

Possible names for this new cheat include startChangePrank or startAndChangePrank. Alternatively, the startPrank cheat could itself be modified to work like this, which would make changePrank redundant.

Side note: I opened this issue here rather than forge-std due to the ongoing plan to implement all cheats natively in Foundry (#3782).