Reaction highlights (#1145)

* Highlight own reactions

- Highlight own reactions on timeline and improve style.
- Highlight reactions on message bottom sheet only when it our own.

* Improve overlay background colours

* pin to new sdk version

* Remove the red used for debug.

* Fix padding, overlap and only display count if > 1.

- Fix reaction padding and overlap of reaction and bubble.
- Only display count if greater than 1.
- Return EmptyView for TimelineDeliveryStatus.cancelled.

* Fix colors as per design recommendations.

* Add Snapshot tests for reactions and documentation.

- Add UITests for the timeline including reactions.
- Add the reference snapshots.
- Add documentation on how to run snapshot tests and update the reference snapshots.

* Fix Package.resolved

ElementX/Sources/UITests/UITestsScreenIdentifier.swift

@@ -36,6 +36,7 @@ enum UITestsScreenIdentifier: String {
     case roomPlainNoAvatar
     case roomEncryptedWithAvatar
     case roomSmallTimeline
+    case roomSmallTimelineWithReactions
     case roomSmallTimelineWithReadReceipts
     case roomSmallTimelineIncomingAndSmallPagination
     case roomSmallTimelineLargePagination