move core::pdu and core::state_res into core::matrix::

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

src/core/matrix/pdu/relation.rs

@@ -0,0 +1,22 @@
+use ruma::events::relation::RelationType;
+use serde::Deserialize;
+
+use crate::implement;
+
+#[derive(Clone, Debug, Deserialize)]
+struct ExtractRelType {
+	rel_type: RelationType,
+}
+#[derive(Clone, Debug, Deserialize)]
+struct ExtractRelatesToEventId {
+	#[serde(rename = "m.relates_to")]
+	relates_to: ExtractRelType,
+}
+
+#[implement(super::Pdu)]
+#[must_use]
+pub fn relation_type_equal(&self, rel_type: &RelationType) -> bool {
+	self.get_content()
+		.map(|c: ExtractRelatesToEventId| c.relates_to.rel_type)
+		.is_ok_and(|r| r == *rel_type)
+}