Reaction summary view and sorting reactions by count and then timestamp (#942)

* Sort reactions by count and then timestamp

- Sort reactions within an aggregation by timestamp descending. This puts the most recent at the top, useful in cases like the reaction summary view or getting the most recent reaction.
- Sort aggregated reactions by count and then timestamp ascending, using the most recent reaction in the aggregation. This appends new aggregations on the end of the reaction layout.

* Add reaction summary view

* fix warnings

* Fix test unit tests and add sorting tests

- Fix broken build in test code
- Add a test for reaction sorting

* Remove default closure, move logic to presenter and add tests

* Update screenshots

* Fix imports

* Revert Screenshots I didn't update

* Fix imports remove screetshots

* Update screenshots

* Update screenshots

* Address comments.

* Update screenshots

* Remove unnecessary snapshotFlow

* Fix code quality checks

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Co-authored-by: ElementBot <benoitm+elementbot@element.io>

libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/timeline/item/event/EventReaction.kt

@@ -16,10 +16,7 @@
 
 package io.element.android.libraries.matrix.api.timeline.item.event
 
-import io.element.android.libraries.matrix.api.core.UserId
-
 data class EventReaction(
     val key: String,
-    val count: Long,
-    val senderIds: List<UserId>
+    val senders: List<ReactionSender>
 )

libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/timeline/item/event/ReactionSender.kt

@@ -0,0 +1,31 @@
+/*
+ * Copyright (c) 2023 New Vector 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.
+ */
+
+package io.element.android.libraries.matrix.api.timeline.item.event
+
+import io.element.android.libraries.matrix.api.core.UserId
+
+/**
+ * The sender of a reaction.
+ *
+ * @property senderId the ID of the user who sent the reaction
+ * @property timestamp the timestamp the reaction was received on the origin homeserver
+ */
+data class ReactionSender(
+    val senderId: UserId,
+    val timestamp: Long
+)
+