Distinguish passed tests

[Nashtare]

This makes a distinction between passed tests from a witness-only run vs a proving run, as there is currently no distinction. Now:

• calling -w when running with the -p argument will skip all previously passed tests, regardless of the type of run they went through
• calling -p without specifying -w will only discard previously passed tests with full proving enabled (and will re-run tests where only witness was generated).

I initially wanted to have something like:

pub(crate) enum PassState {
    Passed(PassedStatus),
    Ignored,
    Failed,
    #[default]
    NotRun,
}

but it seems serde and CSV writer don't work well with nested enums?

closes #40

[BGluth]

Thanks for adding this. Didn't occur to me when I added the witness only flag.