Move various e2e defintions out to yaml files (#1166)

We have code to generate tables, which we should use in the e2e section.

data/api/client-server/definitions/megolm_export_session_data.yaml

@@ -0,0 +1,38 @@
+# Copyright 2022 The Matrix.org Foundation C.I.C
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+allOf:
+  - $ref: key_backup_session_data.yaml
+  - type: object
+    description: |-
+      The format used to encode a Megolm session key for export.
+
+      This is similar to the format before encryption used for the session keys
+      in [Server-side key backups](#server-side-key-backups) but adds the
+      `room_id` and `session_id` fields.
+    properties:
+      room_id:
+        type: string
+        description: |-
+          The room where the session is used.
+        example: "!Cuyf34gef24t:localhost"
+      session_id:
+        type: string
+        description: |-
+          The Megolm session ID.
+        example: "X3lUlvLELLYxeTx4yOVu6UDpasGEVO0Jbu+QFnm0cKQ"
+    required:
+      - room_id
+      - session_id