Use an enumerated error for VSS errors

[futurepaul]

Getting "uknown error" when VSS is misconfigured, looks like this is the error that's being thrown:

mutiny-node/mutiny-core/src/vss.rs

Line 180 in 87537f9

MutinyError::Other(anyhow!("Error parsing list key versions url: {e}"))

seems like we can be more concrete than MutinyError::Other?

(if it's one of the errors in the enum it's easier for me to match on because I auto generate a list of potential errors with errorsToTs.cjs)