Add excludeSelector to StdInvariant

[horsefacts]

Most of the invariant test filtering helpers have both target and exclude variants to include or filter contracts/senders/selectors from fuzzing. But there's no corresponding excludeSelector for targetSelector. It's probably a safer practice to start by excluding selectors from a handler contract to avoid forgetting a function or two for large handlers, so it would be useful to have excludeSeclector.

(Secondarily, the naming of targetSelector seems a little odd. It's singular, but the function accepts multiple selectors for a single contract address. It might be clearer as targetSelectors/excludeSelectors plural. I did a double take as I wrote this up, worried that I got it wrong in my examples!)

[mds1]

@mattsse do you mind transferring this to the foundry repo since excludeSelector would be a change to forge itself? (or @horsefacts feel free to close and reopen there, sorry for the confusion)

[horsefacts]

Ah, whoops. I'll move it!

[horsefacts]

Reopened on forge as foundry-rs/foundry#4352