feat: expose account_mut

[gakonst]

as title, we need this to expose a mutable ref to an account so that we can override its nonce in foundry-rs/foundry#554

[sorpaas]

Can you create a set_nonce function in the executor instead?

[gakonst]

@sorpaas The motivation is to avoid having to add a setter for everything because I'd like to have access to full internals, is that a big issue?

I'm OK with it otherwise

[gakonst]

@sorpaas I gave this an attempt locally, it requires changing the Handler trait and implementing a bunch of methods for passing thru the values, I'd really prefer to just expose this function globally as a simple change without further expanding the interfaces elsewhere.

[gakonst]

@sorpaas Updated the PR based on your comment from Matrix!

[gakonst]

Nice - thank you. @sorpaas could we merge? The CI errors seem unrelated.

[sorpaas]

Please merge master and it should fix the CI.

[gakonst]

Rebased! Should be good now. Thanks @sorpaas