Adopt the new start chat button design. (#4013)

* Update compound and handle plain to tertiary/textLink button style updates.

* Update the start chat button to use the right icon/style.

* Update preview snapshots.

* Fix remaining snapshots.

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

@@ -54,7 +54,7 @@ struct IdentityConfirmationScreen: View {
             Button(L10n.actionLearnMore) {
                 UIApplication.shared.open(context.viewState.learnMoreURL)
             }
-            .buttonStyle(.compound(.plain))
+            .buttonStyle(.compound(.tertiary, size: .small))
             .padding(.top, 16)
         }
     }
@@ -85,8 +85,7 @@ struct IdentityConfirmationScreen: View {
                 Button("\(L10n.actionSkip) 🙉") {
                     context.send(viewAction: .skip)
                 }
-                .buttonStyle(.compound(.plain))
-                .padding(.vertical, 14)
+                .buttonStyle(.compound(.tertiary))
             }
         }
     }