[Bug] Accessibility hold overlay should be solid colour (#262)

AzureCommunicationUI/sdk/AzureCommunicationUICalling/AzureCommunicationUICalling/Assets.xcassets/Color/onHoldBackground.colorset/Contents.json

@@ -0,0 +1,38 @@
+{
+  "colors" : [
+    {
+      "color" : {
+        "color-space" : "srgb",
+        "components" : {
+          "alpha" : "1.000",
+          "blue" : "0.898",
+          "green" : "0.898",
+          "red" : "0.898"
+        }
+      },
+      "idiom" : "universal"
+    },
+    {
+      "appearances" : [
+        {
+          "appearance" : "luminosity",
+          "value" : "dark"
+        }
+      ],
+      "color" : {
+        "color-space" : "srgb",
+        "components" : {
+          "alpha" : "1.000",
+          "blue" : "0.000",
+          "green" : "0.000",
+          "red" : "0.000"
+        }
+      },
+      "idiom" : "universal"
+    }
+  ],
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

AzureCommunicationUI/sdk/AzureCommunicationUICalling/AzureCommunicationUICalling/Presentation/Style/ColorThemeProvider.swift

@@ -37,6 +37,7 @@ class ColorThemeProvider {
     let gradientColor = UIColor.compositeColor(.gradientColor)
     let hangup = UIColor.compositeColor(.hangup)
     let overlay = UIColor.compositeColor(.overlay)
+    let onHoldBackground = UIColor.compositeColor(.onHoldBackground)
 
     init(themeOptions: ThemeOptions?) {
         self.colorSchemeOverride = themeOptions?.colorSchemeOverride ?? .unspecified

AzureCommunicationUI/sdk/AzureCommunicationUICalling/AzureCommunicationUICalling/Presentation/SwiftUI/Calling/CallingViewComponent/Overlay/LobbyOverlayView.swift

@@ -17,7 +17,7 @@ struct OverlayView: View {
     let viewModel: OverlayViewModelProtocol
 
     var body: some View {
-        Color(StyleProvider.color.overlay)
+        Color(viewModel.background)
             .overlay(
                 ZStack(alignment: .bottom) {
                     VStack(spacing: 0) {

AzureCommunicationUI/sdk/AzureCommunicationUICalling/AzureCommunicationUICalling/Presentation/SwiftUI/Calling/CallingViewComponent/Overlay/OnHoldOverlayViewModel.swift

@@ -4,6 +4,7 @@
 //
 
 import Foundation
+import UIKit
 
 class OnHoldOverlayViewModel: OverlayViewModelProtocol, ObservableObject {
     private let localizationProvider: LocalizationProviderProtocol
@@ -17,6 +18,10 @@ class OnHoldOverlayViewModel: OverlayViewModelProtocol, ObservableObject {
         return localizationProvider.getLocalizedString(.onHoldMessage)
     }
 
+    var background: UIColor {
+        return StyleProvider.color.onHoldBackground
+    }
+
     var errorInfoViewModel: ErrorInfoViewModel?
 
     @Published var actionButtonViewModel: PrimaryButtonViewModel?

AzureCommunicationUI/sdk/AzureCommunicationUICalling/AzureCommunicationUICalling/Presentation/SwiftUI/Calling/CallingViewComponent/Overlay/OverlayViewModelProtocol.swift

@@ -4,17 +4,20 @@
 //
 
 import Foundation
+import SwiftUI
 
 protocol OverlayViewModelProtocol {
     var title: String { get }
     var subtitle: String? { get }
+    var background: UIColor { get }
     var actionButtonViewModel: PrimaryButtonViewModel? { get }
     var errorInfoViewModel: ErrorInfoViewModel? { get }
     var isDisplayed: Bool { get }
 }
 
 extension OverlayViewModelProtocol {
     var subtitle: String? { return nil }
+    var background: UIColor { return StyleProvider.color.overlay }
     var actionButtonViewModel: PrimaryButtonViewModel? { return nil }
     var errorInfoViewModel: ErrorInfoViewModel? { return nil }
 }

AzureCommunicationUI/sdk/AzureCommunicationUICalling/AzureCommunicationUICalling/Utilities/ColorExtension.swift

@@ -30,6 +30,7 @@ enum CompositeColor: String {
     case gradientColor = "gradientColor"
     case hangup = "hangupColor"
     case overlay = "overlayColor"
+    case onHoldBackground = "onHoldBackground"
 }
 
 extension UIColor {