Tasks

• Bump pimalaya-stream to 0.2 in io-gmail, io-jmap, io-msgraph and io-pim-discovery, with a patch table for stream and io-http, and a changelog entry in each.
• Confirm all four still build with no code change, the stream std and tls APIs being unchanged.
• himalaya: add io-sasl, move the Sasl types off pimalaya-stream and rename them to Sasl*Creds.
• himalaya: supply the SCRAM nonce (empty, drawn by the client) and channel binding the credentials now carry.
• himalaya: ImapClientStdConnectOptions to ImapSessionOpenOptions; bring ImapClient and SmtpClient into scope at the call sites.
• himalaya: SmtpClientStd::connect options struct and tuple return; status takes a Cow; imap raw takes bytes; smtp raw takes a Cow.
• himalaya: catch-all arms for the ten SASL mechanisms the config cannot express.
• Build/test/fmt/clippy.
• Log; land.