Fix continuation of JSON deserialization (#42158)

* Repro #42070

* formatting

* namespace

* Fix

* never forget the header

* More tests
- Test continuation at every position inside the tested object
- Many member with primitive and nullable types
- One more level of nested object
- All combinations of class/struct for tested and nested object
- tested and nested object with parametrized ctor for some properties

* Addressed feedback

* Test with original repro data from #42070

* custom converter to ensure the padding is written in front of the tested object

* rename

* test data moved to Strings.resx

src/libraries/System.Text.Json/src/System/Text/Json/Serialization/JsonPropertyInfoOfT.cs

@@ -222,6 +222,9 @@ public override bool ReadJsonAndSetMember(object obj, ref ReadStack state, ref U
             }
             else if (Converter.CanUseDirectReadOrWrite && state.Current.NumberHandling == null)
             {
+                // CanUseDirectReadOrWrite == false when using streams
+                Debug.Assert(!state.IsContinuation);
+
                 if (!isNullToken || !IgnoreDefaultValuesOnRead || !Converter.CanBeNull)
                 {
                     // Optimize for internal converters by avoiding the extra call to TryRead.
@@ -234,7 +237,7 @@ public override bool ReadJsonAndSetMember(object obj, ref ReadStack state, ref U
             else
             {
                 success = true;
-                if (!isNullToken || !IgnoreDefaultValuesOnRead || !Converter.CanBeNull)
+                if (!isNullToken || !IgnoreDefaultValuesOnRead || !Converter.CanBeNull || state.IsContinuation)
                 {
                     success = Converter.TryRead(ref reader, RuntimePropertyType!, Options, ref state, out T value);
                     if (success)
@@ -284,6 +287,9 @@ public override bool ReadJsonAsObject(ref ReadStack state, ref Utf8JsonReader re
                 // Optimize for internal converters by avoiding the extra call to TryRead.
                 if (Converter.CanUseDirectReadOrWrite && state.Current.NumberHandling == null)
                 {
+                    // CanUseDirectReadOrWrite == false when using streams
+                    Debug.Assert(!state.IsContinuation);
+
                     value = Converter.Read(ref reader, RuntimePropertyType!, Options);
                     success = true;
                 }