Compound - Swift 6.2 and Main actor isolation (#5109)

* compound is now using 6.2 and main actor isolation + some tweaks to make it build tests and EX

* better handling of the nonisolated context for CompoundUIColors

* improving docs

* fix comment

* remove unused Sendable conformance

ElementX/Sources/Screens/Timeline/View/Style/TimelineItemSendInfoLabel.swift

@@ -112,6 +112,7 @@ private struct TimelineItemSendInfoLabel: View {
 }
 
 /// All the data needed to render a timeline item's send info label.
+@MainActor
 private struct TimelineItemSendInfo {
     enum Status {
         case sendingFailed
@@ -185,6 +186,7 @@ private extension TimelineItemSendInfo {
     }
 }
 
+@MainActor
 private extension EncryptionAuthenticity {
     var foregroundStyle: SwiftUI.Color {
         switch color {