Move raw API and event schemas into /data directory

Historical note: this was originally a series of several commits, spread out
over several weeks. They have been squashed together to make `git annotate`
work properly.

The original commits were:
 * 91ab3934 <Will> 2021-01-25 21:16:42 -0800 Add raw API end event schemas into /data directory
 * aae22f47 <Will> 2021-01-25 21:33:06 -0800 Remove non-data files
 * 1092d4ca <Will> 2021-01-26 20:41:33 -0800 Add data-compatiuble extension (.yaml) to all data files that currently omit one
 * 21060109 <Will> 2021-01-26 20:57:28 -0800 Remove symlink to event-schemas, and update openAPI schema paths accordingly
 * 4f633845 <Travis Ralston> 2021-04-12 21:54:54 -0600 Fix event schema examples too
 * 301c7b2f <Will> 2021-02-05 10:15:42 -0800 Restore docs describing OpenAPI extensions that we use

data/api/client-server/redaction.yaml

@@ -0,0 +1,96 @@
+# Copyright 2016 OpenMarket Ltd
+#
+# 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.
+swagger: '2.0'
+info:
+  title: "Matrix Client-Server message redaction API"
+  version: "1.0.0"
+host: localhost:8008
+schemes:
+  - https
+  - http
+basePath: /_matrix/client/%CLIENT_MAJOR_VERSION%
+consumes:
+  - application/json
+produces:
+  - application/json
+securityDefinitions:
+  $ref: definitions/security.yaml
+paths:
+  "/rooms/{roomId}/redact/{eventId}/{txnId}":
+    put:
+      summary: Strips all non-integrity-critical information out of an event.
+      description: |-
+        Strips all information out of an event which isn't critical to the
+        integrity of the server-side representation of the room.
+
+        This cannot be undone.
+
+        Any user with a power level greater than or equal to the ``m.room.redaction``
+        event power level may send redaction events in the room. If the user's power
+        level greater is also greater than or equal to the ``redact`` power level
+        of the room, the user may redact events sent by other users.
+
+        Server administrators may redact events sent by users on their server.
+      operationId: redactEvent
+      security:
+        - accessToken: []
+      parameters:
+        - in: path
+          type: string
+          name: roomId
+          description: The room from which to redact the event.
+          required: true
+          x-example: "!637q39766251:example.com"
+        - in: path
+          type: string
+          name: eventId
+          description: The ID of the event to redact
+          required: true
+          x-example: "bai2b1i9:matrix.org"
+        - in: path
+          name: txnId
+          type: string
+          description: |-
+            The transaction ID for this event. Clients should generate a
+            unique ID; it will be used by the server to ensure idempotency of requests.
+          required: true
+          x-example: "37"
+        - in: body
+          name: body
+          required: true
+          schema:
+            type: object
+            example: {
+                "reason": "Indecent material"
+              }
+            properties:
+              reason:
+                type: string
+                description: The reason for the event being redacted.
+      responses:
+        200:
+          description: "An ID for the redaction event."
+          examples:
+            application/json: {
+                  "event_id": "$YUwQidLecu:example.com"
+              }
+          schema:
+            type: object
+            properties:
+              event_id:
+                type: string
+                description: |-
+                  A unique identifier for the event.
+      tags:
+        - Room participation