[Message Actions] Add emoji reactions option (#568)

* Add logic to send message reactions

* Add emoji library, create EmojiPicker component

* Fix bottom sheet behaviors

---------

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

libraries/matrix/test/src/main/kotlin/io/element/android/libraries/matrix/test/room/FakeMatrixRoom.kt

@@ -70,10 +70,14 @@ class FakeMatrixRoom(
     private var setTopicResult = Result.success(Unit)
     private var updateAvatarResult = Result.success(Unit)
     private var removeAvatarResult = Result.success(Unit)
+    private var sendReactionResult = Result.success(Unit)
 
     var sendMediaCount = 0
         private set
 
+    var sendReactionCount = 0
+        private set
+
     var isInviteAccepted: Boolean = false
         private set
 
@@ -124,6 +128,11 @@ class FakeMatrixRoom(
         return Result.success(Unit)
     }
 
+    override suspend fun sendReaction(emoji: String, eventId: EventId): Result<Unit> {
+        sendReactionCount++
+        return sendReactionResult
+    }
+
     var editMessageParameter: String? = null
         private set
 
@@ -279,4 +288,8 @@ class FakeMatrixRoom(
     fun givenSetTopicResult(result: Result<Unit>) {
         setTopicResult = result
     }
+
+    fun givenSendReactionResult(result: Result<Unit>) {
+        sendReactionResult = result
+    }
 }