Implement resolvable text segment attributes

Example/OpenSwiftUIUITests/View/ProgressViewUITests.swift

@@ -19,7 +19,7 @@ struct ProgressViewUITests {
         openSwiftUIAssertSnapshot(of: IndeterminateProgressViewExample())
     }
 
-    @Test(.disabled("ResolvableTextSegmentAttribute is not implemented yet"))
+    @Test(.disabled("TextLayoutManager is not implemented yet"))
     func defaultDateProgressLabelInitializers() {
         openSwiftUIAssertSnapshot(of: DefaultDateProgressLabelExample())
     }

Sources/OpenSwiftUICore/View/Text/Resolve/ConfigurationBasedResolvableStringAttribute.swift

@@ -163,6 +163,14 @@ private protocol InvalidationConfigurtaionProvider {
     var invalidationConfiguration: ResolvableAttributeConfiguration { get }
 }
 
+extension ReducedTimelineSchedule: InvalidationConfigurtaionProvider where T1: InvalidationConfigurtaionProvider, T2: InvalidationConfigurtaionProvider {
+    var invalidationConfiguration: ResolvableAttributeConfiguration {
+        var configuration = t1.invalidationConfiguration
+        configuration.reduce(t2.invalidationConfiguration)
+        return configuration
+    }
+}
+
 extension ResolvableAttributeConfiguration.Schedule: InvalidationConfigurtaionProvider {}
 
 extension TimeDataFormatting.Resolvable: InvalidationConfigurtaionProvider {}