Initial implementation of AccountSettings. (#6275)

* Make the UserPreference macro also generate an accessor for the key name.

* Initial implementation of AccountSettings.

- Add an AccountUserDefaults storage with a userID prefix on the key.
- Migrate the 2 values reset by AppSettings.resetSessionSpecificSettings to AccountSettings.

* Rename UserSettings.volatile() to UserSettings.mock()

Given it now has a userID parameter with a default value..

ElementX/Sources/Screens/Onboarding/AnalyticsPromptScreen/View/AnalyticsPromptScreen.swift

@@ -102,6 +102,6 @@ struct AnalyticsPromptScreen_Previews: PreviewProvider, TestablePreview {
     }
     
     static func makeViewModel(showTerms: Bool = true) -> AnalyticsPromptScreenViewModel {
-        AnalyticsPromptScreenViewModel(termsURL: showTerms ? UserSettings.volatile().analyticsTermsURL : nil)
+        AnalyticsPromptScreenViewModel(termsURL: showTerms ? UserSettings.mock().analyticsTermsURL : nil)
     }
 }

ElementX/Sources/Screens/Onboarding/IdentityConfirmationScreen/View/IdentityConfirmationScreen.swift

@@ -142,7 +142,7 @@ struct IdentityConfirmationScreen_Previews: PreviewProvider, TestablePreview {
         userSession.sessionSecurityStatePublisher = CurrentValuePublisher<SessionSecurityState, Never>(.init(verificationState: .unverified, recoveryState: recoveryState))
         
         return IdentityConfirmationScreenViewModel(userSession: userSession,
-                                                   userSettings: .volatile(),
+                                                   userSettings: .mock(),
                                                    userIndicatorController: UserIndicatorControllerMock())
     }
 }

ElementX/Sources/Screens/Onboarding/SessionVerificationScreen/View/SessionVerificationScreen.swift

@@ -289,7 +289,7 @@ struct SessionVerification_Previews: PreviewProvider, TestablePreview {
                                           flow: SessionVerificationScreenFlow = .deviceInitiator) -> some View {
         let viewModel = SessionVerificationScreenViewModel(sessionVerificationControllerProxy: SessionVerificationControllerProxyMock.configureMock(),
                                                            flow: flow,
-                                                           userSettings: .volatile(),
+                                                           userSettings: .mock(),
                                                            mediaProvider: MediaProviderMock(.init()),
                                                            verificationState: state)