separate account_data service methods for room vs global events

Previously we were mashing everything together as RoomAccountDataEvent,
even the global events. This technically worked, because of the hidden
custom fields on the ruma event types, but it's confusing and easy to
mess up. Separate methods with appropriate types are preferable.

src/service/admin.rs

@@ -20,8 +20,9 @@ use ruma::{
             power_levels::RoomPowerLevelsEventContent,
             topic::RoomTopicEventContent,
         },
-        TimelineEventType,
+        AnyGlobalAccountDataEvent, TimelineEventType,
     },
+    serde::Raw,
     signatures::verify_json,
     EventId, MilliSecondsSinceUnixEpoch, OwnedMxcUri, OwnedRoomId,
     OwnedServerName, RoomId, RoomVersionId, ServerName, UserId,
@@ -770,20 +771,18 @@ impl Service {
                     .set_displayname(&user_id, Some(displayname))?;
 
                 // Initial account data
-                services().account_data.update(
-                    None,
+                services().account_data.update_global(
                     &user_id,
-                    ruma::events::GlobalAccountDataEventType::PushRules
-                        .to_string()
-                        .into(),
-                    &serde_json::to_value(PushRulesEvent {
+                    &ruma::events::GlobalAccountDataEventType::PushRules,
+                    &Raw::new(&PushRulesEvent {
                         content: PushRulesEventContent {
                             global: ruma::push::Ruleset::server_default(
                                 &user_id,
                             ),
                         },
                     })
-                    .expect("to json value always works"),
+                    .expect("json serialization should always succeed")
+                    .cast::<AnyGlobalAccountDataEvent>(),
                 )?;
 
                 // we dont add a device since we're not the user, just the