v21.0.0-rc.1

🚨 BREAKING CHANGES

• Changes the uploadContent API, kills off request and browser-request in favour of fetch, removed callback support on a lot of the methods, adds a lot of tests. (#2719). Fixes #2415 and #801.
• Remove deprecated m.room.aliases references (#2759). Fixes element-hq/element-web#12680.

✨ Features

• Remove node-specific crypto bits, use Node 16's WebCrypto (#2762). Fixes #2760.
• Export types for MatrixEvent and Room emitted events, and make event handler map types stricter (#2750). Contributed by @stas-demydiuk.
• Use even more stable calls to /room_keys (#2746).
• Upgrade to Olm 3.2.13 which has been repackaged to support Node 18 (#2744).
• Fix power_level_content_override type (#2741).
• Add custom notification handling for MSC3401 call events (#2720).
• Add support for unread thread notifications (#2726).
• Load Thread List with server-side assistance (MSC3856) (#2602).
• Use stable calls to /room_keys (#2729). Fixes element-hq/element-web#22839.

🐛 Bug Fixes

• Fix IdentityPrefix.V2 containing spurious /api (#2761). Fixes element-hq/element-web#23505.
• Always send back an httpStatus property if one is known (#2753).
• Check for AbortError, not any generic connection error, to avoid tightlooping (#2752).
• Correct the dir parameter of MSC3715 (#2745). Contributed by @dhenneke.
• Fix sync init when thread unread notif is not supported (#2739). Fixes element-hq/element-web#23435.
• Use the correct sender key when checking shared secret (#2730). Fixes element-hq/element-web#23374.