State-reset and security mitigations.

Upgrade Ruma to present.

The following are intentionally benign for activation in a later commit:

- Hydra backports not default.
- Room version 12 not default.
- Room version 12 not listed as stable.

Do not enable them manually or you can brick your database.

Signed-off-by: Jason Volk <jason@zemos.net>

src/core/matrix/event/state_key.rs

@@ -0,0 +1,17 @@
+use std::cmp::Ordering;
+
+use ruma::events::StateEventType;
+use smallstr::SmallString;
+
+pub type TypeStateKey = (StateEventType, StateKey);
+pub type StateKey = SmallString<[u8; INLINE_SIZE]>;
+
+const INLINE_SIZE: usize = 48;
+
+#[inline]
+#[must_use]
+pub fn cmp(a: &TypeStateKey, b: &TypeStateKey) -> Ordering { a.0.cmp(&b.0).then(a.1.cmp(&b.1)) }
+
+#[inline]
+#[must_use]
+pub fn rcmp(a: &TypeStateKey, b: &TypeStateKey) -> Ordering { b.0.cmp(&a.0).then(b.1.cmp(&a.1)) }