Deprecate `foundry-blob-explorers`

[zerosnacks]

It is unused by Foundry and seemingly only used by Signet who should be able to replace it with a native implementation with ease or pin to an existing release: https://github.com/init4tech/node-components/blob/05b681482d0a731e22de3af4a16a14257405263f/crates/blobber/Cargo.toml#L26