Move common voip events to the content, not the actual event

data/event-schemas/schema/core-event-schema/call_event.yaml

@@ -1,7 +1,5 @@
-allOf:
-- "$ref": room_event.yaml
-  description: "All call events share a set of common fields: those of room events
-    and some additional VoIP specific fields."
+description: "The content of all call events shares a set of common fields: those
+  of room events and some additional VoIP specific fields."
 properties:
   call_id:
     type: string

data/event-schemas/schema/m.call.answer.yaml

@@ -2,11 +2,14 @@
     "type": "object",
     "description": "This event is sent by the callee when they wish to answer the call.",
     "allOf": [{
-        "$ref": "core-event-schema/call_event.yaml"
+        "$ref": "core-event-schema/room_event.yaml"
     }],
     "properties": {
         "content": {
             "type": "object",
+            "allOf": [{
+                "$ref": "core-event-schema/call_event.yaml"
+            }],
             "properties": {
                 "answer": {
                     "type": "object",

data/event-schemas/schema/m.call.candidates.yaml

@@ -2,11 +2,14 @@
     "type": "object",
     "description": "This event is sent by callers after sending an invite and by the callee after answering. Its purpose is to give the other party additional ICE candidates to try using to communicate.",
     "allOf": [{
-        "$ref": "core-event-schema/call_event.yaml"
+        "$ref": "core-event-schema/room_event.yaml"
     }],
     "properties": {
         "content": {
             "type": "object",
+            "allOf": [{
+                "$ref": "core-event-schema/call_event.yaml"
+            }],
             "properties": {
                 "candidates": {
                     "type": "array",

data/event-schemas/schema/m.call.hangup.yaml

@@ -22,10 +22,12 @@ description: |
    * `unknown_error`: Some other failure occurred that meant the client was unable to continue the call
       rather than the user choosing to end it.
 allOf:
-- "$ref": core-event-schema/call_event.yaml
+- "$ref": core-event-schema/room_event.yaml
 properties:
   content:
     type: object
+    allOf:
+    - "$ref": core-event-schema/call_event.yaml
     properties:
       reason:
         type: string

data/event-schemas/schema/m.call.invite.yaml

@@ -2,11 +2,14 @@
     "type": "object",
     "description": "This event is sent by the caller when they wish to establish a call.",
     "allOf": [{
-        "$ref": "core-event-schema/call_event.yaml"
+        "$ref": "core-event-schema/room_event.yaml"
     }],
     "properties": {
         "content": {
             "type": "object",
+            "allOf": [{
+                "$ref": "core-event-schema/call_event.yaml"
+            }],
             "properties": {
                 "offer": {
                     "type": "object",

data/event-schemas/schema/m.call.negotiate.yaml

@@ -34,10 +34,12 @@ description: |
   attempt to validate the `type` field, but simply pass the object into the
   WebRTC API.
 allOf:
-- "$ref": core-event-schema/call_event.yaml
+- "$ref": core-event-schema/room_event.yaml
 properties:
   content:
     type: object
+    allOf:
+    - "$ref": core-event-schema/call_event.yaml
     properties:
       offer:
         type: object

data/event-schemas/schema/m.call.reject.yaml

@@ -13,10 +13,12 @@ description: |
 
   The meanings of the `reason` codes are the same as in [`m.call.hangup`](#mcallhangup).
 allOf:
-- "$ref": core-event-schema/call_event.yaml
+- "$ref": core-event-schema/room_event.yaml
 properties:
   content:
     type: object
+    allOf:
+    - "$ref": core-event-schema/call_event.yaml
     properties:
       reason:
         type: string

data/event-schemas/schema/m.call.select_answer.yaml

@@ -2,11 +2,14 @@
     "type": "object",
     "description": "This event is sent by the caller's client once it has decided which other client to talk to, by selecting one of multiple possible incoming `m.call.answer` events. Its `selected_party_id` field indicates the answer it's chosen. The `call_id` and `party_id` of the caller is also included. If the callee's client sees a `select_answer` for an answer with party ID other than the one it sent, it ends the call and informs the user the call was answered elsewhere. It does not send any events. Media can start flowing before this event is seen or even sent.  Clients that implement previous versions of this specification will ignore this event and behave as they did before.",
     "allOf": [{
-        "$ref": "core-event-schema/call_event.yaml"
+        "$ref": "core-event-schema/room_event.yaml"
     }],
     "properties": {
         "content": {
             "type": "object",
+            "allOf": [{
+                "$ref": "core-event-schema/call_event.yaml"
+            }],
             "properties": {
                 "selected_party_id": {
                     "type": "string",