Two fixes. On wasm, arti's guard manager could panic in a client's first
15 seconds and take the WASM instance down (arti fork pinned to
voltrevo/arti@e623ace, which fixes it). Fast bootstrap hashes
microdescriptors in Rust instead of with crypto.subtle, so it works where
crypto.subtle is missing. See CHANGELOG.md.

WASM SHA256:   dc19c462910583c951e9610a0466c14c7fae795cc36a3502652e3c619a945ee6
Worker SHA256: d4628b28e069bdec4897c4511c7e99c35c9aabcd97ae79a8bf58d53f901e7976
Worker keccak256: 0xe39f8c42ed72b7f580a73c46c3300f6d3ad3954bbc26e5fe075b18c48fedc8b5