WrappedAspNetCoreSession doesn't persist updated properties

### Describe the bug

Compare the behaviour of the following between .NET Framework and .NET Core's `AddWrappedAspNetCoreSession`:

- create a class with some simple value properties
- via `System.Web.HttpContext.Current.Session` either
- set a new instance of that class into session
- pull an existing instance of that class out of session
- update a property on the instance; do not explicitly write the instance back to `System.Web.HttpContext.Current.Session`
- read the property in a subsequent call

In .NET Framework, the updated value is automatically persisted into session at the end of the first call.

In .NET Core via `AddWrappedAspNetCoreSession`, the updated value does not appear to be persisted into session at the end of the call unless you manually push the instance back into `System.Web.HttpContext.Current.Session`.

`AspNetCoreSessionState` does not seem to track what values have been added or retrieved and re-push them to the underlying `_session` in `CommitAsync`.

Further, if you retrieve the same value from session twice in _one_ call, in Framework you get the same object, but in Core you get different objects. `AspNetCoreSessionState` does not seem to track what values have been pulled from the underlying `_session` and return the same instances.

### To Reproduce

Similar Web API code running in [Core](https://github.com/rawling/SwaSessionPersistence/blob/master/SwaSessionPersistence.Core/Controllers/WeatherForecastController.cs) and [Framework](https://github.com/rawling/SwaSessionPersistence/blob/master/SwaSessionPersistence.Framework/Controllers/ValuesController.cs).

Run via the [caller](https://github.com/rawling/SwaSessionPersistence/blob/master/SwaSessionPersistence.Caller/Program.cs):

### Further technical details

Please include the following if applicable:

*ASP.NET Framework Application*:
- Technologies and versions used (i.e. MVC/WebForms/etc): WebApi. In-proc session provider. (Observed with SQL session provider too, but not tried with this repro.)
- .NET Framework Version: 4.8
- IIS Version: Express
- Windows Version: 10

*ASP.NET Core Application*:
- Targeted .NET version: 8 (observed in 10 too, but not tried with this repro)
- .NET SDK version:

Start with AspNetCoreSessionState, especially how values are retrieved and how CommitAsync handles the underlying _session. Run the linked SwaSessionPersistence Core and Framework controllers through the caller to compare updated-property persistence and repeated retrieval. Done means Core matches Framework for both behaviors.

Written by the indexing model from the issue text.