Improve the performance of changing the composer mode.

Note: this will only be noticeable once a new version of the RTE library is used and the crash when calling `renderComposerMode` is fixed.

Also, improved the UI for full screen mode.

features/messages/src/main/java/io/element/android/x/features/messages/MessagesScreen.kt

@@ -232,9 +232,9 @@ fun MessagesContent(
                 .imePadding()
                 .let {
                     if (composerFullScreen) {
-                        it.weight(1f)
+                        it.weight(1f, fill = false)
                     } else {
-                        it.height(COMPOSER_HEIGHT)
+                        it.wrapContentHeight(Alignment.Bottom)
                     }
                 },
         )